CH 1 HW
A club wants to sponsor a panel discussion on the upcoming national election. The club wants fourfour of its members to lead the panel discussion. Write a short description of the processes that can be used to generate your sample. Obtain a simple random sample of size 4 from the table. CLUB LIST 1. Blouin 2. Bolden 3. Bolt 4. Carter 5. Cooper 6. Debold 7. Engler 8. Grajewski 9. Hayes 10. Hamilton 11. Keating 12. Lukens 13. May 14. Motola 15. Nolan 16. Ochs 17. Pawlak 18. Ramirez 19. Rice 20. Tate 21. Thompson 22. Washington 23. Williams 24. Wright 25. Zenkel 1. Which of the following would produce a simple random sample? 2. The list of digits below is from a random number generator using technology. Use the list of numbers to obtain a simple random sample of size 4 from this list. If you start with the first number in the list, and take the first four numbers between 1 and 25, what four members would be selected from the numbered list? 19, 9, 22, 21, 7, 15, 24, 3, 14, 1, 25, 16, 3, 16, 10
1. Number the names from 1 to 25 and use a random number generator to produce 4 different numbers corresponding to the names and List each name on a separate piece of paper, place them all in a hat, and pick four. 2. Rice, Hayes, Washington, Thompson
The human resource department at a certain company wants to conduct a survey regarding worker benefits. The department has an alphabetical list of all 4957 employees at the company and wants to conduct a systematic sample of size 50. 1. what is k? 2. Determine the individuals who will be administered the survey. Randomly select a number from 1 to k. Suppose that we randomly select 9.
1. k = 99 ^ 4957/50 = 99.14 -> 99 2. Starting with the first individual selected, the individuals in the survey will be 9, 108, 207, ..., 4860 ^ first one is given = 9, second is 10+k-> 10+99, third is 10 +2(k)-> 10+2(99) and last 10+99(50-1) = 4860
Which allows the researcher to claim causation between an explanatory variable and a response variable?
A designed experiment allows the researcher to claim causation between an explanatory variable and a response variable.
What is a designed experiment?
A designed experiment is when a researcher assigns individuals to a certain group, intentionally changing the value of an explanatory variable, and then recording the value of the response variable for each group.
Define treatment.
Any combination of the values of the factors (explanatory variables)
Determine the level of measurement of the variable. Time of day measured in military time: 1500 1600 1700, 1800 and 1900, what is the correct level of measurement?
Interval
Determine the level of measurement of the variable. Year of birth of college students, what is the correct level of measurement?
Interval
A(n) parameter is a numerical summary of a population.
parameter
Ford wants to administer a satisfaction survey to its current customers. Using their customer database, the company randomly selects 50 customers and asks them about their level of satisfaction with the company. what type of sampling is used?
simple random sampling
A(n) _____ is a numerical summary of a sample.
statistic
A(n) ____ sample is obtained by dividing the population into homogeneous groups and randomly selecting individuals from each group.
stratified sample
What are some solutions to nonresponse?
attempt callbacks and offer rewards and incentives
A(n) _____ sample is obtained by dividing the population into groups and selecting all individuals from within a random sample of the groups.
cluster sample
To determine customer opinion of their pricing, Greyhound Lines randomly selects 100 busses during a certain week and surveys all passengers on the busses. what type of sampling is used?
cluster sampling
A internet site asks its members to call in their opinion regarding their web searching habits. what type of sampling is used?
convenience sampling
________ statistics consists of organizing and summarizing information collected, while ______ statistics uses methods that generalize results obtained from a sample to the population and measure the reliability of the results.
descriptive statistics and inferential statistics
A(n) _________ is a person or object that is a member of the population being studied.
individual
A polling organization contacts 1692 undergraduates who attend a university and live in the United States and asks whether or not they had spent more than $200 on food in the last month. What is the population study? What is the sample study?
population study: undergraduates who attend a university and live in the United States sample study: the 1692 undergraduates who attend a university and live in the United States
To determine her water pressure, Britney divides up her day into three parts: morning, afternoon, and evening. She then measures her water pressure at 2 randomly selected times during each part of the day. what type of sampling is used?
stratified sampling
Which sampling method does not require a frame?
systematic sampliing
To estimate the percentage of defects in a recent manufacturing batch, a quality control manager at Toyota selects every 17th car that comes off the assembly line starting with the eighth until she obtains a sample of 120 cars. what type of sampling is used?
systematic sampling
Generally, the goal of an experiment is to determine the effect that the treatment will have on the response variable. true or false?
true
_________ are the characteristics of the individuals of the population being studied.
variables
What is replication in an experiment?
Replication is applying each treatment to more than one experimental unit.
Suppose that a newspaper predicted that Candidate A would defeat Candidate B in a certain election. They conducted a poll of automobile owners with a response rate of 23%. On the basis of the results, the newspaper predicted that Candidate A would win with 57% of the popular vote. However, Candidate B won the election with about 62% of the popular vote. At the time of this poll, most automobile owners belonged to the party of Candidate A. Name two biases that led to this incorrect prediction.
Sampling bias: Using an incorrect frame led to undercoverage. Nonresponse bias: The low response rate caused bias.
A researcher has decided to test the effectivness of a drug meant to reduce high cholesterol through a completely randomized design. She has obtained 9 volunteers with high cholesterol: Amanda, Brian, Christine, David, Emily, Fred, George, Heather, and Ivan. Number the volunteers 1 through 9, alphabetically. Use the thirdthird row of digits in the random number table below to randomly assign 3 of the volunteers to the experimental group (ignore zeros). The remaining volunteers will go into the control group. List the individuals in each group. Row 1: 12663, 41156, 64016, 98021 Row 2: 16902, 87195, 56738, 04609 Row 3: 63949, 92781, 15758, 58246 1. What are the numbers of the three volunteers selected? 2. List the three individuals assigned to the experimental group. 3. List the remaining individuals assigned to the control group.
1. 6, 3, 9 2. Fred, Christine, Ivan 3. David, Amanda, Heather, Emily, George, Brian
The data below relate to characteristics of high-definition televisions A-E. Identify the individuals, variables and data corresponding to the variables and determine whether each variable is qualitative, continuous or discrete. SETUP SIZE SCREEN TYPE # OF CH A 41 PROJECTION 299 B 51 PROJECTION 114 C 56 PLASMA 425 D 52 PLASMA 270 E 58 PROJECTION 289 1. What are the individuals being studied? 2. What are the variables and their corresponding data being studied? 3. Determine whether each variable is qualitative, continuous, or discrete for size, screen type and number of channels available.
1. Individuals being studied is the high-definition television setups A through E. 2. Size (41, 51, 56, 52, 58), screen type (Projection, Projection, Plasma, Plasma, Projection), and number of channels available (299, 114, 425, 270, 289) 3. Size is a continuous variable, screen type is a qualitative variable and number of channels available is a discrete variable.
To research the claim that green tea lowers LDL (so-called bad) cholesterol, you ask a random sample of individuals to divulge whether they are regular green tea users or not. You also obtain their LDL cholesterol levels. Finally, you compare the LDL cholesterol levels of the green tea drinkers to those of the non-green tea drinkers. 1. Explain why this is an observational study. 2. Name some lurking variables that might exist in the study. 3. Suppose, instead of surveying individuals regarding their tea-drinking habits, you decide to conduct a designed experiment. You identify 120 volunteers to participate in the study and decide on three levels of the treatment: a placebo, one cup of green tea daily, two cups of green tea daily. The experiment is to run for one year. The response variable will be the change in LDL cholesterol for each subject from the beginning of the study to the end. What type of experimental design is this? 4. Explain how you would use blinding in this experiment. 5. What is the factor? Is it qualitative or quantitative? 6. What factors might you attempt to control in this experiment? 7. Explain how to use randomization in this experiment. How does randomization neutralize those variables that are not controlled? Randomly assign the ____ to treatment groups. This will mute the effect of variation attributable to the ___ explanatory variables response variables experimental units that are not controlled. Then any difference in the value of the response variable among the different treatment groups is a result of ____. 8. Suppose you assigned 40 subjects to each of the three treatment groups. In addition, you decided to control the variable exercise by having each subject perform 150 minutes of cardiovascular exercise each week by walking on a treadmill. However, the 40 subjects in the placebo group decided they did not want to walk on the treadmill and skipped the weekly exercise. Explain how exercise is now a confounding variable. Any difference in the change in the ____ cannot be attributed to the ____. It may be the ____ that caused the change in the ______.
1. This is an observational study because there is no intent to manipulate the explanatory variable, whether the individual is green tea drinker or not. 2. Exercise, diet, age, gender and genetics 3. Completely randomized design 4. Do not allow the subjects to know which level of the treatment they are receiving. Also, do not allow the researcher(s) giving the treatments to know which level of the treatment they are giving. This is a double-blind study. 5. The factor is the amount of green tea daily, it is qualitative. 6. Diet and exercise 7. Experimental units , explanatory variables , differences in the level of the treatment. 8. Response variable , treatment level. , exercise, response variable.
To help assess student learning in her reform calculus courses, a calculus professor at a university implemented pre- and post-tests for her reform calculus students. A knowledge-gained score was obtained by taking the difference of the two test scores. 1. What type of experimental design is this? 2. What is the response variable in this experiment? 3. What is the treatment?
1. matched design 2. difference in test scores 3. calculus course
A poll is being conducted on a college campuson a college campus nothingto obtain a sample of the population of an entire country. 1. What is the frame for this type of sampling? 2. Who would be excluded from the survey and how might this affect the results of the survey?
1. the frame is the entire population of the country. 2. any person who does not go to that campus is excluded. This could result in sampling bias due to undercoverage.
A sales person obtained a systematic sample of size 25 from a list of 500 clients. To do so, he randomly selected a number from 1 to 20, obtaining the number 11. He included in the sample the 11th client on the list and every 20th client thereafter. List the numbers that correspond to the 25 clients selected.
11, 31, ..., 491
What is a confounding variable?
A confounding variable is an explanatory variable that was considered in a study whose effect cannot be distinguished from a second explanatory variable in the study.
What is a frame?
A frame is a list of the individuals in the population being studied.
What is a lurking variable?
A lurking variable is an explanatory variable that was not considered in a study, but that affects the value of the response variable in the study. In addition, lurking variables are typically related to explanatory variables in the study.
What does it mean when an observational study is prospective?
A prospective study collects the data over time. Your answer is correct.
What does it mean when an observational study is retrospective?
A retrospective study requires that individuals look back in time or require the researcher to look at existing records.
Define simple random sampling.
A sample of size n from a population of size N is obtained through simple random sampling if every possible sample of size n has an equally likely chance of occurring. The sample is then called a simple random sample.
Define factor.
A variable whose effect on the response variable is to be assessed by the experimenter
A student entering a doctoral program in educational psychology is required to select three courses from the list of courses provided as part of his or her program. A. List all possible three-course selections. B. Comment on the likelihood that EPR 660, EPR 644, and EPR 676 will be selected. List: EPR 660, Interpretive Methods in Educational Research EPR 644 comma Nonparametric Statistics EPR 653 comma Fieldwork Methods in Educational Research EPR 676 comma Educational Research Planning and Interpretation EPR 684 comma Methods of Multivariate Analysis
A. 660, 653, 684 660, 644, 684 660, 644, 676 660, 676, 684 644, 653, 684 644, 676, 684 653, 676, 684 660, 653, 676 644, 653, 676 660, 644, 653 B. There is 1 in 10 chance that these courses will be selected.
Researchers wanted to determine if there was an association between the level of happiness of an individual and their risk of heart disease. The researchers studied 1864 people over the course of 12 years. During this 12-year period, they interviewed the individuals and asked questions about their daily lives and the hassles they face. In addition, hypothetical scenarios were presented to determine how each individual would handle the situation. These interviews were videotaped and studied to assess the emotions of the individuals. The researchers also determined which individuals in the study experienced any type of heart disease over the 12-year period. After their analysis, the researchers concluded that the happy individuals were less likely to experience heart disease. Complete parts (a) through (c). A. What type of observation study was this? Explain. B. What is the response variable? What is thee explanatory variable? C. In the report, the researchers stated that "the research team also hasn't ruled out that a common factor like genetics could be causing both the emotions and the heart disease." Explain what this sentence means.
A. This was a cohort study, because information was collected about a group of individuals by observing them over a long period of time. B. The response variable is whether or not heart disease was contracted, because it is the variable of interest. Meanwhile, the explanatory variable is level of happiness, because it affects the other variables C.The researchers may be concerned with confounding that occurs when the effects of two or more explanatory variables are not separated or when there are some explanatory variables that were not considered in a study, but that affect the value of the response variable.
A polling organization conducts a study to estimate the percentage of households that have Internethave Internet accessaccess. It mails a questionnaire to 1887 randomly selected households across the country and asks the head of each household if he or she has Internet access. Of the 1887 households selected, 17 responded. A. Which of these best describes the bias in the survey? B. How can the bias be remedied?
A. nonresponse bias B. The polling organization should try contacting households that do not respond by phone or face-to-face.
A polling organization conducts a study to estimate the percentage of households that speak a foreign language as the primary language. They mail a questionnaire to 1,023 randomly selected households and asks the head of household if a foreign language is the primary language spoken in ht home. Of the 1,023 households selected, 12 responded. A. determine the bias B. suggest the remedy
A. nonresponse bias B. conduct a face-to-face or telephone interviews
Suppose you are conducting a survey regarding activity level of children activity level of children in a school district. You obtain a cluster sample of 12 schools within a school district and sample all sophomore students in the randomly selected schools. The survey is administered by the parents. A. Which of these best describes the bias in the survey? B. How can the bias be remedied?
A. response bias B. The survey should be administered by an impartial party.
A pro-military advocate wants to estimate the percentage of people who favor increasing funding for funding the military. HeHe conducts a nationwide survey of 1070 randomly selected adults 18 years and older. The interviewer asks the respondents, "Do you favor being patriotic by supporting our armed forces?" A. Which of these best describes the bias in the survey? B. How can the bias be remedied?
A. response bias B. the interviewer should reword the question.
The owner of a shopping mall wishes to expand the number of shops available in the food court. She has a market researcher survey the first 120 customers who come into the food court during weekday afternoons to determine what types of food the shoppers would like to see added to the food court. A. What is the cause of the bias? B. Suggest a remedy to the problem. Which of the following is the best way to remedy this problem?
A. sampling bias B. ask customers throughout the day on both weekdays and weekends
A newspaper article reported, "The famous magazine survey of more than 5,000 women aged 18- 34 found about 42 percent considered themselves overweight or obese." A. what is the type of bias? B. what is a possible remedy?
A. sampling bias B. use systematic random sampling
Define placebo.
An innocuous medication, such as a sugar tablet, that looks, tastes, and smells like the experimental medication
What is an observational study?
An observational study measures the value of the response variable without attempting to influence the value of either the response or explanatory variables.
Define experimental unit
A person, object, or some other well-defined item upon which a treatment is applied
What is a case-control study?
Case-control studies are observational studies that are retrospective, meaning that they require individuals to look back in time or require the researcher to look at existing records.
What is meant by confounding?
Confounding in a study occurs when the effects of two or more explanatory variables are not separated. Therefore, any relation that may exist between an explanatory variable and the response variable may be due to some other variable or variables not accounted for in the study.
What is a cross-sectional study?
Cross-sectional studies are observational studies that collect information about individuals at a specific point in time or over a very short period of time.
In statistical studies, researchers want to determine how varying one or more _______ variables may impact the value of a(n) _______ variable.
Explanatory variables; response variable
Determine whether the following statement is true or false. Explain. When taking a systematic random sample of size n, every group of size n from the population has the same chance of being selected.
False, because certain groups would never be selected.
Determine the level of measurement of the variable. Time of day measured in military time, what is the correct level of measurement?
Interval
Suppose you are interested in comparing brand A interior latex paint to brand B interior latex paint. Design an experiment to determine which paint is better for painting bedrooms.
Matched-pairs design because experimental units are paired up and there are only two levels of treatment.
Which is the superior observational study? Why?
Neither study is always the superior to the other. Both have advantages and disadvantages that depend on the situation.
Researchers wanted to know if there is a link between proximity to high-tension wires and the rate of leukemia in children. To conduct the study, researchers compared the rate of leukemia for children who lived within 1/2 mile of high-tension wires to the rate of leukemia for children who did not live within 1/2 mile of high-tension wires. The researchers found that the rate of leukemia for children near high-tension wires was higher than the rate for those not near high-tension wires. Can the researchers conclude that proximity with high-tension wires causes leukemia in children?
No, because this is an observational study.
Determine the level of measurement of the variable. Eye color, what is the correct level of measurement?
Nominal
Determine the level of measurement of the variable. Favorite musician, what is the correct level of measurement?
Nominal
What does it mean when sampling is done without replacement?
Once an individual is selected, the individual cannot be selected again.
Suppose you are reading an article online when the following text appeared in a popup window: '''Would you be interested in participating in a short health dash related survey? If you qualify and complete this survey, you will receive $ 1.00 .complete this survey, you will receive $1.00.'' What tactic is being used to increase the response rate for this survey?
The company is using a rewards in the form of $1.00 payment
Define confounding.
The effect of two factors (explanatory variables on the response variable) cannot be distinguished.
Define response variable.
The quantitative or qualitative variable for which the experimenter wishes to determine how its value is affected by the explanatory variable
Determine whether the study depicts an observational study or an experiment. Sixth-grade students are randomly divided into two groups. One group is taught math using traditional techniques. The other is taught math using a reform method. After 1 year, each group is given group is given an achievement test to compare its proficiency with that of the other group.
The study is an experiment because the researchers control one variable to determine the effect on the response variable.
Determine whether the study depicts an observational study or an experiment. A study is conducted to determine if there is a relationship between lung capacity and proximity to coal mines. A sample of 100 people living within 1 mile of a coal mine is collected and their lung capacity measured. Does the description correspond to an observational study or experiment?
The study is an observational study because the study examines individuals in a sample, but does not try to influence the response variable.
Determine whether the underlined value is a parameter or a statistic. The average of men who had walked on the moon was 39 years, 11 months, 15 days. [39 years, 11 months, 15 days underlined] Is the value a parameter or a statistic?
The value is a parameter because the men who had walked on the moon are a population.
Determine whether the underlined value is a parameter or a statistic. In a national survey on substance abuse, 66.4% [66.4% is highlighted] of respondents who were full-time college students aged 18 to 22 reported using alcohol within the past month. Is the value a parameter or a statistics?
The value is a statistic because the respondents who were full-time time college students aged 18 to 22 are a sample.
Determine whether the quantitative variable is discrete or continuous. Number of coins in a jar, is the variable discrete or continuous?
The variable is discrete because it is countable.
Determine whether the variable is qualitative or quantitative. Favorite breakfast cereal, is the variable qualitative or quantitative?
The variable is qualitative because it is an attribute characteristics.
Determine whether the variable is qualitative or quantitative. Favorite film, is the variable qualitative or quantitative?
The variable is qualitative because it is an attribute characteristics.
Determine whether the variable is qualitative or quantitative. Number of students at a university, is the variable qualitative or quantitative?
The variable is quantitative because it is a numerical measure.