Alta 1- Sampling and Data

Is the statement below true or false?Quantitative is a numerical characteristic of the sample.

True Quantitative is defined as an attribute whose value is indicated by a number.

The following data set provides the specific sales tax rates for counties in Missouri. A car dealer wants to send out marketing materials in Hartville, Missouri. The marketing materials state that customers will pay the lowest sales taxes in Wright County at her dealership. What is the sample?

The city of Hartville, Missouri A sample is a specific subset of the entire group of individuals being studied. In this case, the sample is the city of Hartville, Missouri.

Given that Justin is collecting data on reaction time, what type of data is he working with?

continuous quantitative Reaction time is continuous quantitative data because it is obtained by measuring and is not limited to a certain set of numbers.

Margaret is investigating if gender has any effect on customer retention. What is the response variable?

customer retention The response variable is the dependent variable, which is the variable that is being measured or tested in response to changes in the independent variable. In this case the response variable is customer retention.

A researcher wants to evaluate the effect of using Facebook on happiness. Would an experimental or observational study design be more appropriate?

An experimental study should be used with the use of Facebook as the controlled factor. An experimental study should be used because the researcher is attempting to control one or more aspects of the individuals in the sample.

Which of the following sampling scenarios describes convenience sampling? Select all that apply.

A computer software store conducted a marketing study by interviewing potential customers who happened to be in the store browsing through the available software. The customers interviewed were in the sample. An administrative assistant was asked to stand in front of the library one Wednesday, and to ask the first 100 undergraduate students he encountered what they paid for tuition the Fall semester. Those 100 students were the sample.

The following data set provides information on New York Senate Employees Payroll. Which sampling approach would give the best results for determining the mean salary of RA employees?

Choosing a starting point at random and selecting RA data even spaces apart for at least 30 employees Systematic sampling from option B produces more accurate results than convenience sampling, which is the method described in options A and C. Choice D does not give the mean, unless the data is known to be absolutely symetrical and normally distributed. Systematic sampling includes the steps: list the members of the population, use simple random sampling to select a starting point in the population, let k = (number of individuals in the population)/(number of individuals needed in the sample), choose every kth individual in the list starting with the one that was randomly selected.

A sampling bias is _______.

Correct answer: the situation in which not all members of the population are equally likely to be selected A sampling bias is defined as the situation in which not all members of the population are equally likely to be selected.

The following data set provides the specific sales tax rates for counties in Missouri. A car dealer in Hartville, Missouri wants to state that customers will pay the lowest sales taxes in Wright County at her dealership. What is the population?

Every city in Wright County The population is the entire group of individuals being studied. In this case, the population is every city in Wright County.

The following data set provides New York City school based programs cost by borough. Sarah calculated the average tuition fee for the school based programs and announced that Staten Island had the best programs for the least amount. "It is five-hundred thousand dollars under the average cost, and it ranks number 2 out of the 5 boroughs, which is way above average." Why is this statistic misleading?

Her opinion relies on two definitions of the word "average." The statistic for the mean of school based programs is calculated. The phrase "way above average" does not have a statistical meaning.

A statistics student is doing a project for her class. She wants to make a prediction for the outcome of an upcoming national election. Since there are only two candidates, she decides that her question is "Which candidate do more people favor in the upcoming election?" She decides to randomly interview 100 students crossing the courtyard on campus about their preference. Is this sample good for drawing general conclusions about the results of the election?

No. The results are not generalizable because the students at her school are not representative of the population of all voters. Since the students at a college are not representative of the population of a country as a whole, even a well-chosen random sample of the students is not generalizable to the whole population. The results should not be considered useful for predicting the outcome of the election.

Key Terms

Observational study: a study in which no attempt is made to control any aspect of the individuals in the sample Experimental study: a study in which the researchers attempt to control one or more aspects of the individuals in the sample

The following data set provides information on New York Senate Employees Payroll.

Sampling bias Sampling bias takes place when the data analyst does not objectively consider all the data, but instead makes a subjective judgment. The auditor has preconceived ideas about the match between gender and first names.

The following data set provides information on New York Senate Employees Payroll. The auditor decides that the Senate needs feedback about a salary differential between male and female employees. Using everyone's first names, she divides the data into two groups. What kind of activity has taken place?

Sampling bias Sampling bias takes place when the data analyst does not objectively consider all the data, but instead makes a subjective judgment. The auditor has preconceived ideas about the match between gender and first names.

A syringe industry advertises that their average cost for a single syringe is $74. Given that their costs are $11, $84, $94, and $107, why is this statistic misleading?

The data contains an outlier. The average of these costs is accurate, but the advertised average is misleading because so many of the cost are well above this level. The very low cost is an outlier and brings the average down to a misleading value.

HR is reviewing the complaints of all coworkers at their company. They sample the coworker population by selecting every 18th coworker from an alphabetical list of the coworkers. Which type of sampling is used?

systematic sampling This scenario demonstrates systematic sampling. Systematic sampling involves selecting every nth individual from the list of individuals in the population based on a randomly selected starting position.

The following data set provides information on New York Senate Employees Payroll. If the auditor added up the contents of the payments, and divided by the number of employees, to get the mean salary, what kind of activity has taken place?

Nonsampling error Non sampling error occurs when the measurement of the data is not correct. The auditor can calculate the mean of the hourly rates of payment for that bi-week. The auditor can calculate the mean of the biweekly rates of payment for the bi-week. However, the auditor cannot calculate the mean salary of the entire group of employees. Other calculations and information would be needed to find the mean salary.

Which of the following represents the population in the scenario below? A researcher wants to know what percentage of people who live in Germany are satisfied with their government spending. Surveys are sent to people who live in the city limits of Berlin, Frankfurt, and Munich.

People who live in Germany The researcher wants to learn about the satisfaction of all the people in Germany, so this is the population.

The following data set provides information on New York Senate Employees Payroll. If the auditor sampled only the employees working in the capital city of Albany to represent the entire state of New York, what kind of activity has taken place?

Sampling bias Sampling bias takes place when the data analyst does not objectively consider all the data, but instead makes s subjective judgment. The sample from Albany may be quite different than from Rochester.

Sneha is inspecting the average cleanliness of the rooms in a hotel. There are 10 floors in the hotel, each with 20 rooms. From each floor, she randomly selects 2 rooms and inspects them and then takes the average of these scores. What type of sampling did Sneha use?

Stratified sampling Because she sampled proportionally from each floor, this is stratified sampling. Each floor is a subgroup, and she randomly selected the same number from each subgroup.

The following data set provides information on New York Senate Employees Payroll.

Which sampling approach would give the best results for determining the mean salary of RA employees?

Thomas wants to estimate the mean height of students attending his college. He records the heights of 25 randomly selected students attending the college. What is the parameter?

the mean height of all students attending the college A parameter is a number that is used to represent a population characteristic. In this case, the parameter is the mean height of all students attending the college.

Anna wants to estimate the mean number of siblings for each student in her school. She records the number of siblings for each of 75 randomly selected students in the school. What is the statistic?

the mean number of siblings for the randomly selected students A statistic is a numerical characteristic of the sample. In this case, the statistic is the mean number of siblings for the randomly selected students.

Timothy wants to estimate the number of customers that are satisfied with the company's branding. He surveys 100 randomly selected customers to determine whether or not they were satisfied. What is the parameter?

the number of all customers that would be satisfied with the company's branding A parameter is a number that is used to represent a population characteristic. In this case, the parameter is the number of all customers that would be satisfied with the company's branding

The following data set provides analysis of the performance of business loans which were identified as being made to a franchise. If the investor uses simple random sampling to create a set of 10 groups, and then analyzed all the individuals in two groups, what kind of sampling is she doing?

Cluster Cluster sampling uses simple random sampling to select a set of groups. Every franchise in the chosen group is included in the sample.

The following data set provides analysis of the performance of business loans which were identified as being made to a franchise. If the investor sorts the list into franchises whose names she recognizes, uses only that data, what kind of sampling is she doing?

Convenience Convenience sampling uses the easiest method of gathering data. It does not have the objectivity of random sampling.

There are 6,000 people who attended a technology conference at a convention center. There are three start-up companies who are participating in the conference - CP Technologies, X-Performance, and A-Robotics. You want to find out which company is most popular amongst the people attending. You ask 500 people as they walk into the convention center. Which represents the population in this scenario?

Correct answer: The 6,000 people attending the conference

True or False? Stratified sampling was used in the scenario below. A random number generator is used to select a client from the alphabetical listing of all client accounts created from January 2016 - December 2016. Starting with that client, every 50th client is chosen until 75 clients are included in the sample.

False

Select all of the following scenarios below that contain nonbiased samples. Select all that apply:

To estimate the mean number of days to ship products at his company, Samuel collects data from a randomly selected proportionate number of shipments from each company site. David wants to estimate the mean returns of products at his website. He collects data by recording the returns of every 25th product on the list of products after a randomly selecting first product. Helen wants to estimate the male to female ratio of the customers of her stores. She collects data by recording the sex of every 50th customer after selecting a random starting point on a list of customers. A sample is biased if some individuals of the population are more or less likely to be selected than others. The sample from choice B is nonbiased because every shipment has an equal chance of being selected. The sample from choice C is nonbiased because every product has an equal chance of being selected. The sample from choice D is nonbiased because every customer has an equal chance of being selected.

Rebecca is investigating if age has any effect on clothings sales. What is the response variable?

clothings sales The response variable is the dependent variable, which is the variable that is being measured or tested in response to changes in the independent variable. In this case the response variable is clothing sales.

Which of the following best describes the term explanatory variable?

the independent variable in an experiment An explanatory variable is defined as the independent variable in an experiment.

Susan wants to estimate the mean number of ads for each facebook page. She records the number of ads for each of 200 randomly selected facebook pages. What is the population?

all facebook pages The population is the entire group of individuals being studied. In this case, the population is all facebook pages

Ruby is studying the mean vacation time of all coworkers working at her company. She collects data from the 25 coworkers in her department. Which type of sampling is used?

convenience sampling This scenario demonstrates convenience sampling. Convenience sampling involves selecting individuals from the population that are easily accessible, or from which data is easily obtained.

To study the mean sales of all people in her company, Jacqueline collects data from 20 randomly selected people in her department. Which type of sampling is used?

convenience sampling This scenario demonstrates convenience sampling. Convenience sampling involves selecting individuals from the population that are easily accessible, or from which data is easily obtained.

In order to study the mean video views of people on his website, Richard samples the population by dividing the viewers by age and randomly selecting a proportionate number of viewers from each age group. Which type of sampling is used?

stratified sampling This scenario demonstrates stratified sampling. Stratified sampling involves dividing the population into groups and randomly selecting a proportionate number of individuals from each group.

The following data set provides the specific sales tax rates for counties in Missouri. The city of Hartville is in Wright County. Find Hartville's sales tax. Which of the following statements are true? Select all that apply.

0.081 is a parameter of Hartville. Both 8.1% and 0.081 are parameters of Hartville. Hartville's sales tax is 8.1% or 0.081. A parameter is a number describing a population, not a sample, characteristic. Parameters (and statistics) can be expressed as either numbers or percentages. In this case, the parameter is the tax rate for the population of Hartville, Missouri. A statistic decribes a sample, not a population, characteristic. No survey of a random sample of residents occurred.

Data are individual items of information that come from a population or sample. Data may be classified as qualitative, quantitative discrete, or quantitative continuous.

Data are individual items of information that come from a population or sample. Data may be classified as qualitative, quantitative discrete, or quantitative continuous.

True or False: The subjects are blinded in the study (above) by the Scent Company.

False Subjects will clearly know whether they can smell flowers or not, so subjects cannot be blinded in this study.

The following data set is from the Dictionary to Understand Survey Responses in May 2017. The data set explains questions and types of responses. What level of variables are "Start Date" and "End Date"?

Interval Interval scale level - Data that is measured using this numerical scale has a definite order, and the differences between interval scale data can be measured. Since time of day does not have a true zero value, it is not ratio data.

The following data set provides information on New York Senate Employees Payroll. The auditor knows the codes for the payment types. TE = Temporary Employee or Hourly Rate, RA = Regular Annual, SA = Special Annual. In looking at the column of data about payments, cell contents range from two to four digits. Is this an example of sampling error?

No Sampling error is not present. The column reports data about employees' payments either biweekly or hourly, and does not distinguish between the two methods of salary determination

A 2016 Gallup poll collected data on people's political party affiliation for the upcoming presidential election. People either affiliated themselves as "Republican," "Democratic," or "Independent." Is this data qualitative or quantitative discrete, or quantitative continuous?

Qualitative This data is qualitative data because it is the result of categorizing or describing attributes of a population. Quantitative discrete data are numbers which are the result of counting, and take only certain numerical values. Quantitative continuous data are numbers which are the result of measuring.

The following data set provides analysis of the performance of business loans which were identified as being made to a franchise. If the investor groups the franchises by type of food focused upon, and then uses simple random sampling to identify a proportionate number of franchises from each group, what kind of sampling is she doing?

Stratified Stratefied sampling selects a characteristic, such as type of food focused on, to create subpopulations to sample. Stratified sampling includes the steps: divide the population into groups, use simple random sampling to identify a proportionate number of individuals from each group.

The following data set provides analysis of the performance of business loans which were identified as being made to a franchise. If the investor divides the franchises into subgroups by the number of disbursements, and selects 10% of each group, what kind of sampling is she doing?

Stratified Stratified sampling selects a characteristic, such as the number of disbursements, to create subpopulations to sample. Stratified sampling includes the steps: divide the population into groups, use simple random sampling to identify a proportionate number of individuals from each group.

A researcher is interested in the effects of watching videos just before bed on the quality of sleep. He has decided to test the claim "Watching 1 hour of video just before going to bed reduces the number of minutes of REM sleep by more than 10%." How should the number of hours of video be treated?

The number of hours of video should be controlled. Some measurements should be done for 1 hour of video and some should be done with no video. The number of hours of video is an experimental factor that needs to be controlled. The claim specifies 1 hour. So there should be a test set for people who watched 1 hour of video and a control set for people who watched no video.

Rebecca collected data from a random sample of 500 women from her website asking whether or not they prefer liquid eyeliner or pencil. Based on the results, she reports that 51% of the women in the nation use liquid eyeliner. Why is this statistic misleading?

The sample is biased. The sample in this case is biased. The individuals included in the sample are not representative of the entire population because eyeliners preferred may be different based on different regions or websites used in the country.

In a study to identify the effectiveness of drugs in reducing smoking habits, the study participants were grouped into 3 categories. Each of the groups was assigned randomly to one type of drug, either Drug A, Drug B, or Drug C. Results were observed for a 4 week period. Is the study observational or experimental? If it is an experiment, what is the controlled factor?

The study is an experiment. The controlled factor is the drug types. The samples are chosen using an appropriate process; however, no attempt is made to control any aspect of the sample even though the variables of interest are recorded for each group.

A survey was conducted among school students on the relationship between getting up late and getting to school late. Is this an example of an observational study or experimental study? If it is an experiment, what is the controlled factor?

The study is an observational study. The samples are chosen using an appropriate process; however no attempt is made to control any aspect of the sample even though the variables of interest are recorded for each group.

In a study to support drug discovery for patients with lung cancer, patients were divided into 3 groups based on the severity of the disease. Smoking and alcohol consumption habits were recorded for all 3 groups. Is this an example of an observational study or experimental study?

The study is an observational study. The samples are chosen using an appropriate process; however, no attempt is made to control any aspect of the individuals in the sample, even though the variables of interest are recorded for each group.

In a study to add a new feature to a software program, the programmer introduced two categories, men and women, in the survey she conducted. Is the study observational or experimental? If it is an experiment, what is the controlled factor?

The study is an observational study. The samples are chosen using an appropriate process; however, no attempt is made to control any aspect of the sample even though the variables of interest are recorded for each group.

To determine whether or not grade level influences money spent at a music shop, Samuel has designed a survey. What is the response variable?

money spent at a music shop The response variable is the dependent variable, which is the variable that is being measured or tested in response to changes in the independent variable. In this case the response variable is money spent at a music shop.

The following data set provides the specific sales tax rates for counties in Missouri. A car dealer wants to send out marketing materials in Hartville, Missouri. The marketing materials state that customers will pay the lowest sales taxes in Wright County at her dealership. What is the sample?

A car dealer wants to send out marketing materials in Hartville, Missouri. The marketing materials state that customers will pay the lowest sales taxes in Wright County at her dealership. What is the sample?

Which of the following surveys have quantitative data? Select all correct answers.

A 2015 CDC Survey on family growth asked women how many times they have been pregnant. A survey on youth health asked participants for the number of sports they played in the previous week. It is helpful to look for clues that tell you when data is quantitative. Phrases like how many or the number of indicate that data is quantitative. Phrases like which type or what kind indicate qualitative data. So in this question, how many times is quantitative data. Also, number of sports is quantitative.

You want to determine the overall grade point average (GPA) at your school. There are 1,800 students at your school. Since you want to collect data about all of the students, all 1,800 students is the population. But, it would be difficult to ask every single one of the 1,800 students in your school about his/her GPA. So, it would make sense to gain information from a smaller group of students who attend your school. So, you survey 200 random students. This portion of the population is called the sample. The grade point averages of the students surveyed would be the data collected. A statistic and a parameter are both descriptions of groups, but they represent different groups.

A parameter is a number that is a property of the population. Sometimes, when the population is small enough, there is no need to take a sample, and so determining a parameter is easier and a more accurate reflection of the population. For this example, the parameter would be the overall GPA of all 1,800 students at your school. A statistic is a number that represents a property of the sample. The statistic is an estimate of a population parameter. For this example, the statistic is the GPA for the 200 random students.

Which of the following scenarios contains a sampling error?

A study is conducted to determine the favorite business area of all the students in your School of Business. Students in your Economics 101 section were used as the sample.

Which of the following is continuous data? Select all correct answers.

A survey management company measured how much time each participant takes to complete a survey. An environmental researcher measured the average length of the fish in a certain lake. Time and length are both continuous data because they can be fractions or decimals. For example, the time to complete a survey may be 4.5 minutes. The average length of the fish might be 15.2 centimeters.

A researcher wants to find out the effect of the amount of protein eaten at breakfast on the aerobic performance of runners. Would an experimental or observational study design be more appropriate?

An experimental study should be used where the amount of protein eaten at breakfast is the controlled factor. An experimental study should be used because the goal involves a cause and effect relationship.

A study is planned to research the effects of drinking coffee on hours of sleep. Would an experimental or observational study design be more appropriate?

An experimental study should be used where the consumption of coffee is the experimental factor. An experimental study should be used because the goal involves a cause and effect relationship.

A biologist wants to study the effect of vitamin D enriched food on the weight of adult mice. Would an experimental or observational study design be more appropriate?

An experimental study should be used where the food consumed is the controlled factor. An experimental study should be used because the goal involves a cause and effect relationship.

Which of the following best describes the term response variable?

the dependent variable in an experiment A response variable is defined as the dependent variable in an experiment.

An energy drink manufacturer wants to find out the effect of different amounts of their product on the maximum anaerobic power level for rowers. Would an experimental or observational study design be more appropriate?

An experimental study should be used with the amount of the drink consumed as the controlled factor. An experimental study should be used because the goal involves a cause and effect relationship.

A scientist is interested in finding out the effect of soil quality on crop quality. Would an experimental or observational study design be more appropriate?

An experimental study should be used with the soil quality as the controlled factor. An experimental study should be used because the goal involves a cause and effect relationship.

Which of the following scenarios contain nonbiased samples? Select all that apply.

Andrea wants to estimate the mean salary of managers at her company. She collects data by recording the salaries of all managers included in 12 randomly selected departments. To estimate the male to female ratio of the residents of his city, Charles collects data by recording the sex of every 50th resident after selecting a random starting point on a list of residents. A sample is biased if some individuals of the population are more or less likely to be selected than others. The sample from choice A is nonbiased because every manager has an equal chance of being selected. The sample from choice D is nonbiased because every resident has an equal chance of being selected.

Angela wants to estimate the mean number of runners for each track team. She records the number of runners of 20 randomly selected track teams. What is the data? Data are the result of sampling from a population. Data are the actual values of the variable. The data in this example is the specific number of runners for each randomly selected track team.

Angela wants to estimate the mean number of runners for each track team. She records the number of runners of 20 randomly selected track teams. What is the data? Data are the result of sampling from a population. Data are the actual values of the variable. The data in this example is the specific number of runners for each randomly selected track team.

The following data set provides a pediatric research study using healthy controls for the vitamin D status of children with inflammatory bowel disease (IBM). The researcher found that overweight/obese controls had significantly lowered Vitamin D compared to normal weight individuals. What is the explanatory variable?

BMI level The explanatory variable is the independent variable, which is the variable that is changed to determine its effect on a dependent variable. In this case, the explanatory variable is the BMI level.

A researcher is interested in the effects of watching videos just before bed on the quality of sleep. He has decided to test the claim "Watching 1 hour of video just before going to bed reduces the number of minutes of REM sleep by more than 10%. " Which of the following data collection processes would be appropriate? Select only one answer choice.

Choose a random sample of people. On multiple randomly selected nights, randomly assign each person to either watch one hour of video or not watch video and monitor their sleep. To perform an experiment, a control group that does not watch video and a test group that does should be used. It is also important for the process to account for possible confounding variables. In this case both the person and the night of the week could be confounding variables. By choosing random nights and having the same people either watch 1 hour of videos or not, variations due to the person and the night of the week should not interfere with the analysis.

Which of the following scenarios contain nonbiased samples? Select all that apply.

Christine wants to estimate the mean sales of coworkers at her company. She collects data by recording the sales average of every 25th coworker on the list of coworkers after a randomly selecting first coworker. Homer wants to estimate the ethnic background distribution of residents of his regional sales area. He collects data from 1000 randomly selected residents in his region by using a random number generator. To estimate the mean salary of managers at his company, Peter collects data by recording the salaries of all managers included in 12 randomly selected departments. A sample is biased if some individuals of the population are more or less likely to be selected than others. The sample from choice A is nonbiased because every coworker has an equal chance of being selected. The sample from choice B is nonbiased because every resident has an equal chance of being selected. The sample from choice D is nonbiased because every manager has an equal chance of being selected.

The following data set provides analysis of the performance of business loans which were identified as being made to a franchise. An investor is offered a partnership deal on a franchise business. She wants to confirm if franchises can succeed by sampling from the over 500 cases measured by the Small Business Administration. If she examines the first 50 rows of their spreadsheet, what kind of sampling is she doing?

Convenience Convenience sampling uses the easiest method of gathering data. It does not have the objectivity of random sampling.

The following data set provides a pediatric research study using healthy controls for the vitamin D status of children with inflammatory bowel disease (IBM). The researcher found that overweight/obese controls had significantly lowered Vitamin D compared to normal weight individuals. What could be lurking variables in the study? Select all that apply.

Diet Sun exposure Hair color Race Diseases Lurking variables have an effect on a study's outcome, even though they are neither independent nor dependent variables. Different dietary intake or diseases might alter Vitamin D levels. Different races could have different skin colors that might prevent Vitamin D creation with sun exposure.

Select the scenario below that demonstrates sampling bias.

Elizabeth wants to estimate the mean vacation days of coworkers at her company. She collects data by selecting a random group of coworkers within her department. A sample is biased if some individuals of the population are more or less likely to be selected than others. The sample from choice C is biased because the coworkers in her department only represent one department, which vacation days could be more or less in general than other departments.

The following data set provides a pediatric research study using healthy controls for the vitamin D status of children with inflammatory bowel disease (IBM). Labels of weight status were added, such as under 18.5 = underweight, 18.5 to 24.9 = healthy, 25 to 29.9 = overweight, 30 or higher = obese. Which variables do these labels describe?

Explanatory The explanatory variable is the independent variable, which is the variable that is changed to determine its effect on a dependent variable. In this case, the explanatory variable is the BMI level.

Researchers are investigating whether taking aspirin regularly reduces the risk of heart attacks. Four hundred men participate in the study. The men are divided randomly into two groups: one group takes aspirin pills, and the other group takes placebo pills (a pill with no aspirin in it). The men each take one pill a day, and they do not know which group they are in. At the end of the study, researchers will count the number of men in each group who have had heart attacks.Identify the explanatory and response variables in this situation.

Explanatory variable: the type of pill the men took each day Response variable: whether a subject had a heart attack An explanatory variable explains or influences changes in another variable. The affected variable, the variable that is changed by altering the explanatory variable, is called the response variable.In an experiment, the researcher manipulates values of the explanatory variable and measures the resulting changes in the response variable.

Is the statement below true or false?Continuous is the type of quantitative data that is the result of counting.

False Continuous data is defined as the type of quantitative data that is the result of measuring.

The following data set provides New York City school based programs cost by borough. Jenny expected the school based programs to cost over four million. With that expectation, how many programs would she find in the data that meet this expectation?

Four Four school based programs have costs above $4,000,000.

The following data set provides a pediatric research study using healthy controls for the vitamin D status of children with inflammatory bowel disease (IBM). If the researcher decides to explore the role of gender in Vitamin D deficiency, what is the explanatory variable?

Gender The explanatory variable is the independent variable, which is the variable that is changed to determine its effect on a dependent variable. In this case, the explanatory variable is the gender.

A seed corn company keeps track of the daily temperature, in degrees Fahrenheit, of a field over the course of six weeks. What is the level of measurement of the data?

Interval This is interval data because degrees Fahrenheit is a numerical scale where differences are meaningful. However, because Fahrenheit does not have a true zero value, it is not ratio data.

A manager keeps track of the time of day that junior members leave work. What is the level of measurement of the data?

Interval This is interval data because time of day is a numerical scale where differences are meaningful. However, because the time of day does not have a true zero value, it is not ratio data.

A new mother keeps track of the time on a 12-hour clock when her baby wakes up each morning. What is the level of measurement of the data?

Interval This is interval data because time of day is a numerical scale where differences are meaningful. However, because the time of day on a 12 hour clock does not have a true zero value, it is not ratio data.

Joseph wants to estimate the mean number of deputies for each senior officer in his town. He records the number of deputies for each of 20 randomly selected senior officers in the town. What is the sample? A sample of the population is a smaller portion of the larger population taken to do a study. The sample in this example is the 20 randomly selected senior officers.

Joseph wants to estimate the mean number of deputies for each senior officer in his town. He records the number of deputies for each of 20 randomly selected senior officers in the town. What is the sample? A sample of the population is a smaller portion of the larger population taken to do a study. The sample in this example is the 20 randomly selected senior officers.

Which of the following scenarios demonstrates sampling bias?

Kathryn wants to estimate the mean amount of money spent on clothes per week by mall shoppers. She collects data from every 10th person entering one clothing store at the mall. A sample is biased if some individuals of the population are more or less likely to be selected than others. The sample from choice B is biased because mall shoppers that do not visit this particular store are not represented.

What do the statistics of mode and mean measure?

Mode: Most frequent sales tax rate. Mean: Average sales tax rate. The following are the definitions of the mode and mean. Mode: Most frequnt sales tax rate. Mean: Average sales tax rate.

The following data set provides information on New York Senate Employees Payroll. If the auditor was paid by the New York Senate, would her work monitoring them be subject to sampling bias?

No Even if the auditor was paid by the New York Senate, her activity would not constitute sampling bias. She has no control over the numbers in the spreadsheet.

The following data set provides New York City school based programs cost by borough. Bryce summarized the report of the school based programs: "The more the cost in programs, the better the school." Is that summary consistent with the data?

No The data does not show that for every extra dollar spent on a program, the better the school is.

The following data set is from the Dictionary to Understand Survey Responses in May 2017. The data set explains questions and types of responses. Looking at the dictionary for the survey about autonomous cars, what level of variable is "AV Safety Potential"?

Nominal Nominal scale level - Data that is measured using this scale is qualitative and not ordered.

The following data set is from the Dictionary to Understand Survey Responses in May 2017. The data set explains questions and types of responses. What level of variable is "Interact Pedestrian'?

Nominal Nominal scale level - Data that is measured using this scale is qualitative and not ordered.

A market researcher surveys households and asks what brand of shampoo is preferred. What is the level of measurement of the data?

Nominal This is nominal data because the brands of shampoo do not have an order to them. Even though a person may have a personal preference, there is no ranking that is universal.

In 2014, the website PhoneArena polled users, asking them which smartphone company had the best phone that year. The responses were the company names, such as Apple, Motorola, Nokia, Samsung, and Microsoft.Which of the following scale levels describes the data in this poll?

Nominal scale level This data should be measured with a nominal scale level, because data measured on this scale level cannot be ordered nor can it be used in calculations. This is just a list of phone companies, and there is no agreed upon order. Some people may favor Apple but that is a matter of opinion.

The following data set is from the Dictionary to Understand Survey Responses in May 2017. The data set explains questions and types of responses. What level of variable is "AdvocacyIssues"?

Ordinal Ordinal scale level - Data that is measured using this scale can be ordered.

The following data set is from the Dictionary to Understand Survey Responses in May 2017. The data set explains questions and types of responses. What level of variable is "PayingAttentionAV"?

Ordinal Ordinal scale level - Data that is measured using this scale can be ordered.

A hotel asks its patrons to fill out a customer satisfaction survey to rate the service. The options are Very Dissatisfied, Somewhat Dissatisfied, Somewhat Satisfied, Very Satisfied. What is the level of measurement of the data?

Ordinal This is ordinal data because the values are ordered but do not have a meaningful numerical value.

A market researcher surveys users of a certain laundry detergent if they think the detergent makes their laundry smell Very Bad, Bad, Neutral, Good, or Very Good. What is the level of measurement of the data?

Ordinal This is ordinal data because the values are ordered but do not have a meaningful numerical value.

A political researcher asks people if they Strongly Disagree, Disagree, Agree, or Strongly Agree with various policy decisions. What is the level of measurement of the data?

Ordinal This is ordinal data because the values are ordered but do not have a meaningful numerical value.

Which of the following scale levels would be best to measure the data - the heat ratings of different hot sauces - "hot," "hotter," "hottest"?

Ordinal scale level This data should be measured with an ordinal scale level, because data measured on this scale level can be ordered, but there is no way to use the responses in calculations. There would be no way to determine how much more heat "hottest" has than "hotter."

Patrick wants to estimate the percentage of students that use youtube to study. He asks a randomly selected group of 125 students whether or not they use youtube to study. What is the statistic? A statistic is a number that represents a property of the sample. The statistic in this example is the percentage of surveyed students that use youtube to study.

Patrick wants to estimate the percentage of students that use youtube to study. He asks a randomly selected group of 125 students whether or not they use youtube to study. What is the statistic? A statistic is a number that represents a property of the sample. The statistic in this example is the percentage of surveyed students that use youtube to study.

Qualitative Data

Qualitative data are the result of categorizing or describing attributes of a population. Qualitative data are generally described by words or letters. For example, hair color, blood type, ethnic group, the brand of car a person drives, and the type of shampoo a person uses are examples of qualitative data. For instance, the qualitative data for people's hair color might be "black," "dark brown," "light brown," "blonde," "gray," or "red."

Qualitative data: the result of categorizing or describing attributes of a population, usually described by words or lettersQualitative data is also commonly referred to as Categorical data Quantitative data: the result of counting or measuring attributes of a population, always described by numbers, and can be either continuous or discrete Quantitative discrete data: the result of counting, so only can be certain numerical values Quantitative continuous data: the result of measuring

Qualitative data: the result of categorizing or describing attributes of a population, usually described by words or lettersQualitative data is also commonly referred to as Categorical data Quantitative data: the result of counting or measuring attributes of a population, always described by numbers, and can be either continuous or discrete Quantitative discrete data: the result of counting, so only can be certain numerical values Quantitative continuous data: the result of measuring

Quantitative Data

Quantitative data are the result of counting or measuring attributes of a population - they are always numbers. For example, amounts of money, pulse rate, weight, number of residents of a town, and the number of students in a high school are examples of quantitative data. Researchers often prefer to use quantitative data over qualitative data because it lends itself more easily to mathematical analysis. For example, it does not make sense to find an average of people's hair colors or blood types.

Quantitative data may be either continuous or discrete:

Quantitative discrete data are all data which are the result of counting. These data take on only certain numerical values. For example, if you count the number of phone calls you receive for each day of the week, you might get values such as 0, 1, 2, 3, etc (countable numbers). Quantitative continuous data are all data which are the result of measuring, assuming we can measure accurately. For example, measuring angles in radians might result in such numbers as π6, π4, π2, π, 3π4, and so on. If you and your friends carry backpacks with books in them to school, the numbers of books in the backpacks are discrete data and the weights of the backpacks are continuous data.

Ralph wants to estimate the average number of coworkers that bike to work. He asks a randomly selected group of 25 coworkers whether or not they bike to work. What is the parameter? A parameter is a number that is a property of the population. The parameter in this example is the average number of all coworkers that bike to work.

Ralph wants to estimate the average number of coworkers that bike to work. He asks a randomly selected group of 25 coworkers whether or not they bike to work. What is the parameter? A parameter is a number that is a property of the population. The parameter in this example is the average number of all coworkers that bike to work.

The following data set is from the Dictionary to Understand Survey Responses in May 2017. The data set explains questions and types of responses. If the survey asked for the number of pedestrians on any given day, what is the level of measurement?

Ratio Ratio scale level - Data that is measured using this scale addresses ratios and gives you the most information about the data. Ratio scale data is like interval scale data, but it has a starting point (also known as a "0 point") and ratios between the differences can be calculated.

A track runner keeps track of how long it takes her to run the 200 meter dash. What is the level of measurement of the data?

Ratio This is ratio data because length of time has a true zero, and ratios are meaningful. If someone took twice as long to run the 200 meters, then that person ran half as fast.

A market researcher finds the price of several brands of cold medications. What is the level of measurement of the data?

Ratio This is ratio data because price has a true zero, and ratios of prices are meaningful.

study 2

Researchers want to understand the effect of performance-enhancing drugs. One group of participants were given the active performance-enhancing drug, and the other groups were given placebo pills (pills with no active drug). The results showed that if a person simply believed that he or she had taken the drug, their performance times were almost as fast as those subjects who had actually consumed the active pills with the drug itself. In contrast, people who took the drug without knowing they were, resulted in no significant performance increase. A researcher must design an experiment in such a way that there is only one difference between the groups being compared: the planned treatments. (In Study 2, the planned treatments are the types of pill each subject took - pills containing the performance-enhancing or the placebo pills.) Then a researcher must randomly assign the treatments. When this happens, all of the potential lurking variables are spread equally among the groups. Now, the different outcomes measured in the response variable, are a direct result of the different treatments. In this way, an experiment can prove a cause-and-effect connection between the explanatory and response variables.

A study was performed with a random sample of 5 people from a certain city. What population would be appropriate for generalizing conclusions from the study, assuming the data collection methods used did not introduce biases?

The conclusions apply only to the sample. The sample size is very small, so it is not likely to be representative of the city or any larger population.

A study was performed with a random sample of 200 people from one college. What population would be appropriate for generalizing conclusions from the study, assuming the data collection methods used did not introduce biases?

The conclusions should apply to people at that particular college. The sample should represent people at that college reasonably well because it is not very small and was randomly chosen from all the people there. However, the population of that college is probably not representative of the population in any larger context, so further generalization should not be used.

The following data set provides analysis of the performance of business loans which were identified as being made to a franchise. If the investor sorts the list alphbetically, starts at the second franchise, and selects every tenth franchise, what kind of sampling is she doing?

Systematic Systematic sampling selects a simple random starting point in the population. To find out the pattern of selction for the sample, the investor calculates "k," the number of individuals in the population divided by the number needed in the sample. She chooses every kth franchise in the list, starting with the simple random starting point.

A consumer research company is interested in determining if a certain company's new refrigerator model is more efficient than the older model. Researchers decide to investigate the claim that the new model uses 10% less electricity than the older model for the same cooling load. Which data collection method is appropriate? Select only one answer choice.

The company should obtain random samples of each model, place them in similar conditions, fill them with the same amount of water bottles, and monitor their electrical usage over one month. A random sample of both models needs to be used to account for variation in the individual units. The cooling loads should also be equivalent, so they should be in similar conditions with similar contents.

A study was performed with a random sample of 513 bolts produced at one factory. What population would be appropriate for generalizing conclusions from the study, assuming the data collection methods used did not introduce biases?

The conclusions would apply to all bolts produced by that factory. Since the sample is fairly large and was randomly obtained, the results should apply to the bolts made at the factory in the study. However, there could be systematic differences between that factory and any other run by the same company, so the results should not be generalized any further.

In 1936, The Literary Digest conducted a large sample survey of over 2 million Americans to see who they intended to vote for in the presidential election. To identify participants, they used telephone directories, lists of magazine subscribers, and rosters of clubs. 1936 was the middle of the Great Depression; many Americans were unemployed and telephones were a luxury. The Literary Digest predicted that the Republican candidate, Governor Alfred Landon, would get 57% of the vote against Franklin D. Roosevelt's 43%. Is this data misleading? If so, why?

The data is misleading because the sample is biased. The company wanted to survey all Americans, but sampled people who owned telephones, subscribed to magazines, or joined clubs. This is a biased sample, because during the Great Depression, telephones were still a luxury and many people were unemployed. The sample would be biased towards middle- and upper-class Americans. This makes the data and conclusion misleading for the survey the company wanted to conduct.

Which of the following graphs show qualitative data?

The data shown by the first graph are professions and are described by words, so this graph shows qualitative data. The third graph shows the division of two categories - Non-Verbal and Verbal. This is qualitative data because it is not data values of numbers. It cannot be counted or measured.

Brian researched how a person's online purchase behavior is affected by time spent on social media. During the first month participants didn't access social media and reported the amount of online purchases. On the second month, individuals recorded the time spent on social media and the amount of online purchases. What is the response variable in this experiment?

The difference on amount of online purchases from the first month to the second month. Online purchases vary from person to person, which is why Brian has the subjects recorded their online purchases during the first month and no access to social media. He expects the time on social media will affect the amount of their online purchases.

You want to know if there is a relationship between the amount of time a student spends studying for an exam and that student's grade on the exam. Identify the explanatory and response variables in this situation.

The explanatory variable is the amount of time the student spends studying for the exam. The response variable is the student's grade on the exam.When you alter the time the student studies (explanatory), this change will affect change in the student's grade (response). You can imagine that as the amount of time spent studying increases, this positively affects the student's grade, which probably increases as well.

The Power of Suggestion & Importance of Blinding

The power of suggestion can have an important influence on the outcome of an experiment. Studies have shown that the expectation of the people participating in the study can affect the outcome just as much as the actual medication itself. So, researchers must set aside one group as a control group. This group is given the placebo treatment-the treatment that cannot influence the response variable. (The control group in Study 2 is the group given the placebo pills.) Blinding in a randomized experiment counteracts the altering power of suggestion. When a person involved in a research study is blinded, he/she does not know who is receiving the active treatments (in the study above, this would be the aspirin pills) and who is receiving the placebo treatment (the pills without aspirin). A double-blind experiment is one where both the subjects and the researchers are blinded.The accurate understanding of consumer behavior during the research process relies on the correct identification of variables, the elimination of lurking variables and diminishing the power of subjection in individuals.

A large manufacturing firm is interested in the effect of the temperature of the manufacturing floor on worker productivity. Over the course of a year, the firm randomly samples its 103 sites and records the temperature and the quantity of items produced on that day. Is this an experiment or an observational study?

The research is an observational study because the firm did not control any aspects of the sample units. Both the temperature and the quantity of items produced were variables that were measured.

The following data set provides the specific sales tax rates for counties in Missouri. An online clothing store wants to locate in a city in Worth County, Missouri that has the lowest sales tax rate. What mode will he find in the data?

The sales tax rates for Worth County are 0.061, 0.071, 0.081, 0.061, 0.061, 0.061. The value 0.061 occurs four times in the data set while the values 0.071 and 0.081 each occur once. Therefore 0.061 is the mode.

Howard collected data from a random sample of 600 people in his department asking whether or not they use the company's healthcare . Based on the results, he reports that 48% of the people in his company use the company's healthcare. Why is this statistic misleading?

The sample is biased. The sample in this case is biased. The individuals included in the sample are not representative of the entire population because the people in his department do not necessarily have the same healthcare as the people in the rest of the company.

Kenneth collected data from a random sample of 800 voters in his city asking whether or not they would vote to reelect the current governor. Based on the results, he reports that 64% of the voters in his state would vote to reelect the current governor. Why is this statistic misleading?

The sample is biased. The sample in this case is biased. The individuals included in the sample are not representative of the entire population because the voters in his city do not necessarily have the same opinion as the rest of the state.

The following data set provides New York City school based programs cost by borough. Edward looked at the report of school programs and concluded that 60% of the school programs in New York City cost more than $1,542,952. He used only 10 data points from the whole data set. Why is this statistic misleading?

The sample size is insufficient. A sample size of 10 is insufficient to make a prediction.

After asking 8 randomly selected individuals from her airline whether or not they prefer business or first class, Kathryn reports that 63% of the individuals from her airline prefer business on her airline based on her survey. Why is this statistic misleading?

The sample size is insufficient. Although the sampling was random, using such a small sample size to draw conclusions about a much larger number of individuals is bound to be unreliable. This sample size is too small.

After asking 9 randomly selected customers from her store if they buy either fresh or frozen produce but not both, Susan reports that 33% of the customers from her store buy fresh produce based on her survey. Why is this statistic misleading?

The sample size is insufficient. Although the sampling was random, using such a small sample size to draw conclusions about a much larger number of individuals is bound to be unreliable. This sample size is too small.

A farmer divided his land into 2 groups of sections randomly. There is no difference in the quality of the soil between the 2 groups of land. He used Type A seeds in the first group and Type B seeds in the second group. After 3 months, the heights of the crops are measured across the two groups of land sections. Is the study observational or experimental? If it is an experiment, what is the controlled factor?

The study is an experiment. The controlled factor is the seed type. Since the land is divided into two groups and each group is treated with a different type of seed, the study is an experiment. The type of seed is the controlled factor.

A biology student is interested in the relationship between temperature and germination time for soy beans. The student gets sample seeds from multiple sources and randomly selects 180 seeds from them. Then he sets up three growing stations, one at 20∘C, one at 15∘C, and one at 25∘C. He divides the seeds into three groups of 60 and plants the seeds from each group in a growing station. He records the germination time for each seed. Is this an observational study or an experiment? If it is an experiment, what is the controlled factor?

The study is an experiment. The controlled factor is the temperature. Since the seeds are divided into three groups and each group is subjected to a controlled temperature, the study is an experiment. The temperature is the controlled factor.

An opinion poll was conducted to know whether parents play a role in shaping a career for their children. Respondents were asked to vote "Yes" if they think parents have a role to play and "No" if they think parents have no role to play in shaping the career of their children. Is the study observational or experimental? If it is an experiment, what is the controlled factor?

The study is an observational study. The samples are chosen using an appropriate process; however, no attempt is made to control any aspect of the sample even though the variables of interest are recorded for each group.

In a survey conducted to find out the feedback of a sports program organized in a club, the organizers asked the respondents to classify their feedback as good, fair, poor, and bad. Is the study observational or experimental? If it is an experiment, what is the controlled factor?

The study is an observational study. The samples are chosen using an appropriate process; however, no attempt is made to control any aspect of the sample even though the variables of interest are recorded for each group.

Is a survey of the guests about their preference of food at a party an observational study or experimental study? If it is an experiment, what is the controlled factor?

The study is an observational study. The samples are chosen using an appropriate process; however, no attempt is made to control any aspect of the sample even though the variables of interest are recorded for each group.

Is an online poll asking the preferred mobile phone type used by school children an observational study or experimental study? If it is an experiment, what is the controlled factor?

The study is an observational study. The samples are chosen using an appropriate process; however, no attempt is made to control any aspect of the sample even though the variables of interest are recorded for each group.

An established Scent Company conducted a study to investigate whether smell affects sleeping habits. Subjects were exposed to a floral smell wall plug-in while sleeping for 3 nights and 3 nights without. Participants were randomly assigned whether they would be exposed to the floral-scented during the first 3 nights or during the last 3 nights. Researchers found that participants slept longer during the nights with the floral-scented wall plug-ins than the nights without.Which of the following could be lurking variables in this study? Select all that apply.

The subject's impression of the floral scent - positive, neutral, or negative The strength of the subject's sense of smell The subject's age Lurking variables are additional variables that can cloud a study's outcome. This impression of the scent could be influencing the subject's sleep, if he or she does or does not like the floral scent of the wall plug-in. The strength of the subject's sense of smell could be influencing the subject's sleep, because a stronger sense of smell means the scent would affect the subject more. Age may affect how well the subject sleeps, so it is also a lurking variable.

There are 100 Senators in the U.S. Senate. 20 Senators voted against a bill last month. This number is an example of a parameter, because it is a number that represents the whole population.There are 12,000 people at a football stadium. You want to determine the average number of miles people drove to the stadium. Instead of surveying the whole population of 12,000 people, you randomly choose 1,000 people as your sample. The average number of miles driven to the stadium by the sample is an example of a statistic.

There are 100 Senators in the U.S. Senate. 20 Senators voted against a bill last month. This number is an example of a parameter, because it is a number that represents the whole population.There are 12,000 people at a football stadium. You want to determine the average number of miles people drove to the stadium. Instead of surveying the whole population of 12,000 people, you randomly choose 1,000 people as your sample. The average number of miles driven to the stadium by the sample is an example of a statistic.

Observational and Experimental Studies

There are two primary ways to collect data from a new sample: an observational study and an experimental study. Both of these methods involve choosing a sample of individuals from the population and recording the value of one or more variables for each individual. However, there are some differences. In an observational study, no attempt is made to control any aspect of the individuals in the sample. The sample is chosen using an appropriate process, and the variables of interest are recorded for each individual. This kind of study is typically used when it is difficult, unethical, or impossible to control factors in the sample. An observational study is also commonly used when there are no factors that would need to be controlled. Here are a few examples where an observational study would be used: A study on the relationship between smoking and the risk of lung cancer A study on the relationship between premature birth and early reading skills A survey of the opinions of residents on a proposed addition to the local school In an experimental study, the researchers attempt to control one or more aspects of the individuals in the sample. The individuals in the sample will be randomly divided into multiple groups or cases. Then the controlled factors will be set for each of the groups as chosen by the researchers. This may be more clear with a few examples of experimental studies: Researchers randomly assign individuals to three groups. One group listens to no music, one group listens to a top 40 channel from a streaming service, and one group listens to individually selected music. The researchers then give the subjects a cognitive test. An agricultural agency divides 100 plots into two groups. One group receives no pesticides and the other group receives pesticide treatments. The crop yields of each plot are measured at the end of the season.

A study was conducted to determine whether a new highway should be built next to the river in a town. Half of the residents in the town live near the river. The sample of this study consisted of all the residents in the town who live near the river. Which of the following describes the sampling of this study?

There is sampling bias. Sampling bias exists in this study because the people who live near the river probably have stronger opinions about a new highway being placed next to their homes than the rest of the residents in the town who do not live close to the river.

Select all of the following scenarios below that contain nonbiased samples.

To estimate the mean number of days to ship products at his company, Samuel collects data from a randomly selected proportionate number of shipments from each company site. David wants to estimate the mean returns of products at his website. He collects data by recording the returns of every 25th product on the list of products after a randomly selecting first product. Helen wants to estimate the male to female ratio of the customers of her stores. She collects data by recording the sex of every 50th customer after selecting a random starting point on a list of customers. A sample is biased if some individuals of the population are more or less likely to be selected than others. The sample from choice B is nonbiased because every shipment has an equal chance of being selected. The sample from choice C is nonbiased because every product has an equal chance of being selected. The sample from choice D is nonbiased because every customer has an equal chance of being selected.

Which of the following scenarios contain biased samples? Select all that apply.

To estimate the mean project completions of technicians in his company, Donald collects data by recording completions from the warehouse area. Kenneth wants to estimate the mean market shares of his company. He collects data by selecting a random group of coworkers within one department. A sample is biased if some individuals of the population are more or less likely to be selected than others. The sample from choice A is biased because completions in the warehouse area will be different than the other areas/departments. The sample from choice B is biased because the market shares only represent one department and all other coworkers do not have an equal chance of selection to represent all sales in the company.

Is the statement below true or false?A nonsampling error is an issue that affects the reliability of sampling data other than natural variation.

True A nonsampling error is defined as an issue that affects the reliability of sampling data other than natural variation.

A sampling bias is the situation in which not all members of the population are equally likely to be selected.

True A sampling bias is defined as the situation in which not all members of the population are equally likely to be selected.

Is the statement below true or false?Data is a set of observations or possible outcomes.

True It is true that data is defined as a set of observations or possible outcomes.

Which of the following is most likely an example of a non-sampling error? Select all correct answers.

Two researchers distribute paper questionnaires to find out which of several candidates for city council is preferred before the election. The first researcher realizes later that several of the questionnaires he distributed had misprinted and left off one of the candidates. Two researchers create an online poll to find out whether people primarily use a computer, a smartphone, or a tablet to surf the web. After collecting their data, they realize that a bug made it harder for people with a smartphone to submit a response to the survey.

The following data set provides a pediatric research study using healthy controls for the vitamin D status of children with inflammatory bowel disease (IBM). If the researcher decides to explore the role of gender in Vitamin D deficiency, what is the response variable?

Vitamin D level The response variable is the dependent variable, which is the variable that is being measured or tested in response to changes in the independent variable. In this case, the response variable is the Vitamin D level.

The following data set provides a pediatric research study using healthy controls for the vitamin D status of children with inflammatory bowel disease (IBM). The researcher found that overweight/obese controls had significantly lowered Vitamin D compared to normal weight individuals. What is the response variable in the study?

Vitamin D level The response variable is the dependent variable, which is the variable that is being measured or tested in response to changes in the independent variable. In this case, the response variable is the Vitamin D level.

A researcher is interested in the effects of watching videos just before bed on the quality of sleep. Which of the following claims would be appropriate for this situation? Select only one answer choice.

Watching 1 hour of video just before going to bed reduces the number of minutes of REM sleep by more than 10%. The claim or question needs to be testable in order to be analyzed using a statistical process. By using a specified number of hours of video and making a quantitative claim about the effect on REM sleep, the claim can be tested using an appropriate data set.

When collecting the data, you choose a Saturday morning and send a person to each of the five stores in the city. You have them use a die to choose the people to interview by rolling the die each time a person leaves the store and only interviewing a person if the roll is a 1. Will this method produce a random sample that is representative of the population?

While the die-rolling method is a reasonable way to randomly choose shoppers leaving the store, there is a problem with the sampling method. The shoppers in the sample will all be from people who were shopping on Saturday morning. The sampling method could result in a biased sample.

Raymond wants to estimate the percentage of coworkers that use the company's healthcare. He asks a randomly selected group of 200 coworkers whether or not they use the company's healthcare. What is the data?

specific "yes" or "no" responses to the survey Data is a set of observations. In this case, the data is specific "yes" or "no" responses to the survey.

A consumer research company is interested in determining if a certain company's new refrigerator model is more efficient than the older model. What should the researchers do first?

Write a claim about the efficiency of the new model that can be tested. The researchers are at the starting point of the process. They first need to create a question or claim that is testable.

A candy manufacturer is interested in the distribution of colors in each of its packages of candy sold. What should the researchers do first?

Write a question about the distribution of colors in each package. The researchers are at the starting point of the process. They first need to create a question or claim that is testable.

The following data set provides New York City school based programs cost by borough. Ramsesh liked to impress his colleagues with his statistical ability. "Since the mode is $1,188,013, any school based program under that cost is below average." What kind of misleading information is he offering? Select all that apply.

Wrong calculation of the mode. Wrong use of the mode parameter. Ramsesh is confusing the word "mode" with the word "mean," which is the average of the entire population of school based programs in New York City. Both the mean and the mode values for this data set relate to population parameters, not statistics obtained by sampling.

The following data set provides the specific sales tax rates for counties in Missouri. For Worth County, is the median the same as the mode for this specific sample?

Yes To find the median we must first arrange the data from smallest to largest: 0.061,0.061,0.061,0.061,0.071,0.081. Therefore the median is 0.061. 0.061 is the most common number in the data so it is the mode. Therefore the median is the same as the mode.

study 1

You want to investigate the effectiveness of vitamin E in preventing disease. You recruit a group of subjects for your sample, and ask them if they take vitamin E regularly. Analyzing the study, you notice that the subjects who take vitamin E regularly are healthier on average than the subjects who do not. Does this study prove that vitamin E is effective in preventing illness and disease? The answer is - It does not. There are many more differences between subjects who do and do not take vitamin E that were not taken into account. People who take vitamin E regularly may also take other steps to improve their health: exercise, diet, other vitamin supplements, choosing not to smoke, etc. Any one of these factors could also be influencing health. These additional variables that can cloud a study are called lurking variables. So, as described, this study does not prove that vitamin E is the key to disease prevention. In order to prove that the explanatory variable is the actual cause of the change in the response variable, it is necessary to isolate the explanatory variable.

Tina has created an experiment to test whether or not age has any effect on the number of views on her website. What is the explanatory variable in this situation?

age The explanatory variable is the independent variable, which is the variable that is changed to determine its effect on a dependent variable. In this case the explanatory variable is age.

In order to study the mean sales of people in his company, Jerry samples the population by dividing the coworkers by regions and randomly selecting 12 of the regions. He collects data from all coworkers in the selected regions. Which type of sampling is used?

cluster sampling This scenario demonstrates cluster sampling. Cluster sampling involves dividing the population into groups and randomly selecting several of these groups.

To study the mean product use of all people in XYZ Stores, Frank samples the population by dividing the customers by stores and randomly selecting 12 of the stores. He then collects data from all the customers in the selected stores. Which type of sampling is used?

cluster sampling This scenario demonstrates cluster sampling. Cluster sampling involves dividing the population into groups and randomly selecting several of these groups.

What is the type of quantitative data that is the result of measuring?

continuous Continuous is defined as the type of quantitative data that is the result of measuring.

Given that Angelina is collecting data on commute distance, what type of data is she working with?

continuous quantitative Commute distance is continuous quantitative data because it is obtained by measuring and is not limited to a certain set of numbers.

Patrick is collecting data on shoe sizes available at a shoe store. What type of data is this?

discrete quantitative Shoe size is discrete quantitative data because it only takes on certain values, such as 5, 5.5, 6, 6.5, etc.

Jason is collecting data on the number of books students read each year. What type of data is this?

discrete quantitative The number of books students read each year is discrete quantitative data because it is obtained by counting.

Angela is collecting data on the number of classes that students take. What type of data is this?

discrete quantitative The number of classes that students take is discrete quantitative data because it is obtained by counting.

Timothy is collecting data on the number of dental cavities. What type of data is this?

discrete quantitative The number of dental cavities is discrete quantitative data because it is obtained by counting.

When considering different sampling methods, stratified sampling includes the steps: _______.

divide the population into groups; use simple random sampling to identify a proportionate number of individuals from each group Stratified sampling includes the steps: divide the population into groups; use simple random sampling to identify a proportionate number of individuals from each group.

Michelle is investigating if gender has any effect on liquor sales. What is the explanatory variable?

gender The explanatory variable is the independent variable, which is the variable that is changed to determine its effect on a dependent variable. In this case the explanatory variable is gender.

When considering different sampling methods, convenience sampling includes the steps: _______.

identify individuals of the population that are easily accessible; obtain data from these individuals Convenience sampling includes the steps: identify individuals of the population that are easily accessible; obtain data from these individuals.

Given that Janet is collecting data on favorite sports teams, what type of data is she working with?

qualitative Favorite sports teams is qualitative data because it involves categorization of non-numerical attributes.

What term best describes data that is an attribute whose value is indicated by a label?

qualitative Qualitative is defined as an attribute whose value is indicated by a label.

Which of the following is the dependent variable in an experiment?

response variable A response variable is defined as the dependent variable in an experiment.

Timothy wants to estimate the mean number of customer retention from his company. He records the number of retentions from 75 randomly selected company sites. What is the statistic?

the mean number of retentions from the randomly selected company sites A statistic is a numerical characteristic of the sample. In this case, the statistic is number of retentions from the randomly selected company sites.

A sampling bias is _______.

the situation in which not all members of the population are equally likely to be selected A sampling bias is defined as the situation in which not all members of the population are equally likely to be selected.

Angela wants to estimate the mean number of ads for each facebook page. She records the number of ads for each of 200 randomly selected facebook pages. What is the data?

the specific number of ads for each randomly selected facebook page Data is a set of observations. In this case, the data is the specific number of ads for each randomly selected facebook page.

Teresa is investigating if salary range has any effect on time spent after hours at work. What is the response variable?

time spent after hours at work The response variable is the dependent variable, which is the variable that is being measured or tested in response to changes in the independent variable. In this case the response variable is time spent after hours at work.