Statistics
d
(c) Explain how different measures may be used to support two completely different positions. Choose the correct answer below. A. Values can be left out of the graph so that the graph supports the position. B. Data can be rearranged on the graph to make the graph support any position. C. The data collected can be changed so that it will support the position. D. The scales used in the graph can significantly affect the message. Also, the variable used to convey the message on the graph can make a large difference as well.
quantitative
A _________ variable is required when drawing a time-series plot.
number
A frequency distribution lists the ______________ of occurrences of each category of data
b
A polling organization conducts a study to estimate the percentage of households that have pets. It mails a questionnaire to 1898 randomly selected households across the country and asks the head of each household if he or she has pets. Of the 1898 households selected, 37 responded. (a) Which of these best describes the bias in the survey? a Sampling bias b Nonresponse bias c Response bias d Undercoverage bias
d
A polling organization conducts a study to estimate the percentage of households that have two incomes. It mails a questionnaire to 18061806 randomly selected households across the country and asks the head of each household if he or she has two incomes. Of the 1806 households selected, 11 responded. (a) Which of these best describes the bias in the survey? a. Undercoverage bias b Sampling bias c Response bias d Nonresponse bias
permutation
A(n) _________ is an ordered arrangement of r objects chosen from n distinct objects without repetition.
individual
A(n) _________ is a person or object that is a member of the population being studied.
A
According to a center for disease control, the probability that a randomly selected person has hearing problems is 0.1450.145. The probability that a randomly selected person has vision problems is 0.0910.091. Can we compute the probability of randomly selecting a person who has hearing problems or vision problems by adding these probabilities? Why or why not? Choose the correct answer below. A. No, because hearing and vision problems are not mutually exclusive. So, some people have both hearing and vision problems. These people would be included twice in the probability. B. Yes, because this is an application of the Addition Rule for Disjoint Events. C. Yes, because hearing and vision are two different senses, and therefore, they are two unique problems. D. No, because hearing problems and vision problems are events that are too similar to one another.
A
Define simple random sampling. Choose the correct answer below. A. 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. B. Simple random sampling is the process of using chance to select individuals from a population to be included in the sample. The sample is then called a simple random sample. C. Simple random sampling is the process of selecting individuals from a population using a convenient sample. The sample is then called a simple random sample. D. Simple random sampling is the process of obtaining a sample of size n from a population of the same size n. The sample is then called a simple random sample.
interval
Determine the level of measurement of the variable below. "time of day in military time"
b
Determine the level of measurement of the variable below. Eye color Choose the correct answer below. A. Ordinal B. Nominal C. Ratio D. Interval
A
Determine the level of measurement of the variable below. Nation of origin Choose the correct answer below. A. Nominal B. Ordinal C. Ratio D. Interval
true
Determine whether the following statement is true or false. Generally, the goal of an experiment is to determine the effect that the treatment will have on the response variable. Choose the correct answer below. true false
A
Determine whether the following statement is true or false. Explain. Inferences based on voluntary response samples are generally not reliable. Choose the correct answer below. A. True, because it is often the case that the individuals who volunteer do not accurately represent the population. B. True, because the group that volunteers may not be a large enough sample size. C. False, because individuals who volunteer are least likely to have personal bias. D. False, because a surveyor cannot force volunteers to respond.
B
Determine whether the following statement is true or false. Explain. When conducting a cluster sample, it is better to have fewer clusters with more individuals when the clusters are heterogeneous. Choose the correct answer below. A. False. It is better to have fewer clusters when the clusters are homogeneous. B. True, because when the clusters are heterogeneous, they are scaled down versions of the population. C. True, because heterogeneous clusters are not likely to resemble population heterogeneity, increasing the number of necessary individuals. D. False, because the proportion of individuals per cluster to the population should not be affected by whether or not the clusters are heterogeneous.
C
Determine whether the following statement is true or false. Explain. When obtaining a stratified sample, the number of individuals included within each stratum must be equal. Choose the correct answer below. A. False. A stratified sample is constructed by successively selecting a stratum at random and then selecting a random individual from within that stratum. With this process, it is unlikely that all strata will be sampled from the same number of times. B. False. When taking a stratified sample, a simple random sample is drawn from one stratum at random. All other strata will not be included in the sample. C. False. Within stratified samples, the number of individuals sampled from each stratum should be proportional to the size of the strata in the population. D. True. Sampling the same number of people from each stratum will result in a sample that is representative of the population at a lower cost than a simple random sample.
B
Determine whether the following statement is true or false. Explain. When obtaining a stratified sample, the number of individuals included within each stratum must be equal. Choose the correct answer below. A. False. A stratified sample is constructed by successively selecting a stratum at random and then selecting a random individual from within that stratum. With this process, it is unlikely that all strata will be sampled from the same number of times. B. False. Within stratified samples, the number of individuals sampled from each stratum should be proportional to the size of the strata in the population. C. True. Sampling the same number of people from each stratum will result in a sample that is representative of the population at a lower cost than a simple random sample. D. False. When taking a stratified sample, a simple random sample is drawn from one stratum at random. All other strata will not be included in the sample.
C
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. Choose the correct answer below. A. True, because since k is chosen randomly, every group has an equal chance of selection. B. True, because any random sampling implies every group has an chance of selection. C. False, because certain groups would never be selected. D. False, because a systematic sample requires a frame
d
Determine whether the quantitative variable is discrete or continuous. Weight of gravel in a pile Is the variable discrete or continuous? A. The variable is discrete because it is not countable. B. The variable is discrete because it is countable. C. The variable is continuous because it is countable. D. The variable is continuous because it is not countable.
D
Discuss the advantages and disadvantages of each type of question. A. Closed questions are harder to analyze, because they limit the responses. Open questions allow respondents to state exactly how they feel, but are easier to analyze due to the variety of answers. B. Closed questions are easier to analyze, because they usually gather more accurate data. Open questions limit the responses, but are harder to analyze since not every viewpoint will be covered. C. Closed questions allow respondents to state exactly how they feel, but are harder to analyze due to the variety of answers and possible misinterpretation of answers. Open questions are easier to analyze, but limit the responses. D. Closed questions are easier to analyze, but limit the responses. Open questions allow respondents to state exactly how they feel, but are harder to analyze due to the variety of answers and possible misinterpretation of answers.
c
Distinguish between nonsampling error and sampling error. Choose the correct answer below. A. Nonsampling error is the error that results from the process of obtaining the data. Sampling error is the error that results from undercoverage, nonresponse bias, response bias, or data-entry errors. B. Nonsampling error is the error that results because a sample is being used to estimate information about a population. Sampling error is the error that results from undercoverage, nonresponse bias, response bias, or data-entry errors. C. Nonsampling error is the error that results from undercoverage, nonresponse bias, response bias, or data-entry errors. Sampling error is the error that results because a sample is being used to estimate information about a population. D. Nonsampling error is the error that results from randomness. Sampling error is the error that results from using a sample to estimate information about a population.
A
Distinguish between nonsampling error and sampling error. Choose the correct answer below. A. Nonsampling error is the error that results from undercoverage, nonresponse bias, response bias, or data-entry errors. Sampling error is the error that results because a sample is being used to estimate information about a population. B. Nonsampling error is the error that results because a sample is being used to estimate information about a population. Sampling error is the error that results from undercoverage, nonresponse bias, response bias, or data-entry errors. C. Nonsampling error is the error that results from the process of obtaining the data. Sampling error is the error that results from undercoverage, nonresponse bias, response bias, or data-entry errors. D. Nonsampling error is the error that results from randomness. Sampling error is the error that results from using a sample to estimate information about a population.
B
Does the level of octane in gasoline affect gas mileage? To answer this question, an automotive engineer obtains 75 cars. Twenty-five of the cars are compact, 25 are full size, and 25 are sport utility vehicles (SUVs). Design an experiment for the engineer. What type of experimental design should the engineer use? A. Matched pair B. Randomized block design C. Completely randomized design D. Case-control
d
Explain what each point on the least-squares regression line represents. Choose the correct answer below. A. Each point on the least-squares regression line represents the y-value of the data set at that corresponding value of x. B. Each point on the least-squares regression line represents one of the points in the data set. C. Each point on the least-squares regression line represents the y-values that would be considered ideal at that corresponding value of x. D. Each point on the least-squares regression line represents the predicted y-value at the corresponding value of x.
combination
Fill in the blank. A ________ is an arrangement of r objects chosen from n distinct objects without repetition and without regard to order.
multipication
Fill in the blank. The word and in probability implies that we use the ________ rule.
quartiles
Fill in the blank. _______ divide data sets in fourths.
False
Identify the given statement as either true or false. The standard deviation is a resistant measure of spread. Choose the correct answer below. True False
inferential
If a polling organization claimed that the results of the survey indicate that 77% of adults in the country believe that the action is acceptable in certain situations, would you say this statement is descriptive or inferential? Why? The statement is __________ because it makes a prediction.
A
If the linear correlation between two variables is negative, what can be said about the slope of the regression line? Choose the correct answer below. A. Negative B. Positive C. More information is needed
one
In a relative frequency distribution, what should the relative frequencies add up to?
D
In their report, the researchers stated that "After adjusting for various demographic and lifestyle variables, daily consumption of two or more servings was associated with a 30% reduced prevalence of high cholesterol." Why was it important to adjust for these variables? A. The researchers wanted to ensure that the sample was large enough in order to perform inference. B. The researchers were sure that various demographic and lifestyle variables had greater influence than daily consumption of two or more servings. C. The researchers wanted to ensure that the study was representative of the entire population, so they were likely to adjust the responses to match actual data collected for the entire population. D. 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.
d
Inferences based on voluntary response samples are generally not reliable. Choose the correct answer below. A. True, because the group that volunteers may not be a large enough sample size. B. False, because a surveyor cannot force volunteers to respond. C. False, because individuals who volunteer are least likely to have personal bias. D. True, because it is often the case that the individuals who volunteer do not accurately represent the population.
experiment
In probability, a(n) ________ is any process that can be repeated in which the results are uncertain.
explanatory variable
In research, one attempts to determine how varying the amount of an _____ ______ affects the value of a response variable. This manipulated variable is the variable that is under the control of the experimenter.
true
Is the following statement true or false? When plotting an ogive, the plotted points have x-coordinates that are equal to the upper limits of each class.
true
Is the statement below true or false? The least-squares regression line always travels through the point (x,y.) Choose the correct answer below. True False
c
Researchers wanted to determine if having a computer in the bedroom is associated with obesity. The researchers administered a questionnaire to 353353 twelve-year-old adolescents. After analyzing the results, the researchers determined that the body mass index of the adolescents who had a computer in their bedroom was significantly higher than that of the adolescents who did not have a computer in their bedroom. What is the explanatory variable? A. The explanatory variable is the number of the adolescents who have a computer in their bedroom. B. The explanatory variable is the body mass index of the adolescents. C. The explanatory variable is whether the adolescent has a computer in the bedroom or not. D. The explanatory variable is the number of the adolescents who participate in the study.
c
Researchers wanted to determine if having a computer in the bedroom is associated with obesity. The researchers administered a questionnaire to 353353 twelve-year-old adolescents. After analyzing the results, the researchers determined that the body mass index of the adolescents who had a computer in their bedroom was significantly higher than that of the adolescents who did not have a computer in their bedroom. What is the response variable in the study? Is the response variable qualitative or quantitative? A. The response variable is the number of the adolescents who have a computer in their bedroom. The response variable is quantitative. B. The response variable is whether the adolescent has a computer in the bedroom or not. The response variable is qualitative. C. The response variable is the body mass index of the adolescents. The response variable is quantitative. D. The response variable is the number of the adolescents who participate in the study. The response variable is quantitative.
a
Researchers wanted to determine if having a computer in the bedroom is associated with obesity. The researchers administered a questionnaire to 353353 twelve-year-old adolescents. After analyzing the results, the researchers determined that the body mass index of the adolescents who had a computer in their bedroom was significantly higher than that of the adolescents who did not have a computer in their bedroom. What type of observational study is this? a. Cross-sectional study b. Case-control study c. Cohort study
B
Researchers wanted to determine if there was an association between daily kale consumption and the occurrence of high cholesterol. The researchers looked at 94,180 women and asked them to report their kale-eating habits. The researchers also determined which of the women had high cholesterol. After their analysis, the researchers concluded that consumption of two or more servings of kale per day was associated with a reduction in high cholesterol. What is the explanatory variable? A. The explanatory variable is the number of individuals who participate in the study. B. The explanatory variable is consumption of kale C. The explanatory variable is the number of individuals who participate in the study who eat two or more servings of kale per day. D. The explanatory variable is whether the woman has high cholesterol or not.
B
Researchers wanted to determine if there was an association between daily kale consumption and the occurrence of high cholesterol. The researchers looked at 94,180 women and asked them to report their kale-eating habits. The researchers also determined which of the women had high cholesterol. After their analysis, the researchers concluded that consumption of two or more servings of kale per day was associated with a reduction in high cholesterol. What is the response variable in the study? Is the response variable qualitative or quantitative? A. The response variable is the number of individuals who participate in the study who eat two or more servings of kale per day. The response variable is quantitative. B. The response variable is whether the woman has high cholesterol or not. The response variable is qualitative. C. The response variable is consumption of kale. The response variable is quantitative. D. The response variable is the number of individuals who participate in the study. The response variable is quantitative.
B
Researchers wanted to determine if there was an association between daily kale consumption and the occurrence of high cholesterol. The researchers looked at 94,180 women and asked them to report their kale-eating habits. The researchers also determined which of the women had high cholesterol. After their analysis, the researchers concluded that consumption of two or more servings of kale per day was associated with a reduction in high cholesterol. What type of observational study was this? Explain. A. This was a cohort study because it identified a group of individuals to participate in the study and observed the group over a long period of time. B. This was a cross-sectional study because all information about the individuals was collected at a specific point in time. C. This was a case-control study because individuals that had a certain characteristic were matched with those that did not.
a
Select all the reasons why time-series plots are used. A. Time-series plots are used to identify trends in the data over time. B. Time-series plots are used to present the relative frequency of the data in each interval or category. C. Time-series plots are used to examine the shape of the distribution of the data. D. Time-series plots are used to identify any outliers in the data.
no
Suppose that a probability is approximated to be zero based on empirical results. Does this mean that the event is impossible? Yes No
a
Suppose you are conducting a survey regarding illicit drug use among nurses in a city. You obtain a cluster sample of 13 hospitals within a city and sample all nurses in the randomly selected hospitals. The survey is administered by the hospital administration. Which of these best describes the bias in the survey? a Response bias b Sampling bias c Nonresponse bias d Undercoverage bias
a
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 bathrooms. Choose the best design for this experiment. A. Matched-pairs design because experimental units are paired up and there are only two levels of treatment. B. Completely randomized design because experimental units are paired up and there are only two levels of treatment.
b
Suppose you are interested in comparing brand A interior enamel paint to brand B interior enamel paint. Design an experiment to determine which paint is better for painting kitchens. Choose the best design for this experiment. A. Completely randomized design because experimental units are paired up and there are only two levels of treatment. B. Matched-pairs design because experimental units are paired up and there are only two levels of treatment.
A
Surveys tend to suffer from low response rates. Based on past experience, a researcher determines that the typical response rate for an e-mail survey is 2020%. She wishes to obtain a sample of 150 respondents, so she e-mails the survey to 1500 randomly selected e-mail addresses. Assuming the response rate for her survey is 20%, will the respondents form an unbiased sample? Explain. Is the sample unbiased? A. No. The survey still suffers from undercoverage (sampling bias), nonresponse bias, and potentially response bias. B. Yes. The number of respondents will be approximately 300, that is, two times greater than the needed size of the sample. C. Yes. The sample was a randomly selected group of e-mail addresses, which does not introduce bias. D. No. The survey was not given to the entire population.
upper
The lower class limit is the smallest value within the class and the _______________ class limit is the largest value within the class.
response variable
The ______ _______ is a quantitative or qualitative variable that represents the variable of interest.
lower
The _______ class limit is the smallest value within the class and the upper class limit is the largest value within the class.
c
The cumulative relative frequency for the last class must always be 1. Why? Choose the correct answer below. A. All the observations are less than the last class. B. The last class must always have at least one value in it. C. All the observations are less than or equal to the last class.
left
The data are skewed _____ if the median is greater than the mean
addition
The word or in probability implies that we use the _________ Rule.
z score
The _______ represents the number of standard deviations an observation is from the mean.
class width
The _________________ is the difference between consecutive lower class limits.
D
To determine customer opinion of their food quality, General Foods randomly selects 140 city blocks during a certain week and surveys all homes within the city blocks. What type of sampling is used? A. Stratified B. Simple random C. Systematic D. Cluster E. Convenience
D
To help assess student learning in her music theory courses, a music professor at a community college implemented pre- and post-tests for her music theory students. A knowledge-gained score was obtained by taking the difference of the two test scores. What is the response variable in this experiment? a The score on the posttest b The score on the pretest c Total in test scores d Difference in test scores
c
To help assess student learning in her music theory courses, a music professor at a community college implemented pre- and post-tests for her music theory students. A knowledge-gained score was obtained by taking the difference of the two test scores. What type of experimental design is this? a Randomized block design b Completely randomized design c Matched pair. d Case-control
d
To help assess student learning in her music theory courses, a music professor at a community college implemented pre- and post-tests for her music theory students. A knowledge-gained score was obtained by taking the difference of the two test scores. What is the treatment? a Type of school b Background of student c Music theory scores d Music theory course
true
True or False: In a probability model, the sum of the probabilities of all outcomes must equal 1.
true
True or False: In a probability model, the sum of the probabilities of all outcomes must equal 1. Choose the correct answer below. False True
A
True or False: When comparing two populations, the larger the standard deviation, the more dispersion the distribution has, provided that the variable of interest from the two populations has the same unit of measure. Choose the correct answer below. A. True, because the standard deviation describes how far, on average, each observation is from the typical value. A larger standard deviation means that observations are more distant from the typical value, and therefore, more dispersed. B. True, because the standard deviation is the difference between the largest and smallest observation. When the standard deviation is larger, there is more distance between the largest and smallest observation, and therefore, more dispersion in the distribution. C. False, because the larger the standard deviation is, the less dispersion the distribution has. D. False, because the standard deviation measures the spread of the distribution, not the dispersion of the distribution.
independent
Two events E and F are ________ if the occurrence of event E in a probability experiment does not affect the probability of event F.
A
What does it mean if a statistic is resistant? Choose the correct answer below. A. Extreme values (very large or small) relative to the data do not affect its value substantially. B. Extreme values (very large or small) relative to the data affect its value substantially. C. An estimate of its value is extremely close to its actual value. D. Changing particular data values affects its value substantially.
A
What does it mean if r equals=0? Choose the correct answer below. A. No linear relationship exists between the variables. B. A relationship does exist between the variables. C. No relationship exists between the variables. D. A linear relationship does exist between the variables.
C
What does it mean to say that the linear correlation coefficient between two variables equals 1? What would the scatter diagram look like? Choose the correct answer below. A. When the linear correlation coefficient is 1, there is a perfect horizontal linear relation between the two variables. The scatter diagram would contain points that all lie on a horizontal line. B. When the linear correlation coefficient is 1, there is a perfect negative linear relation between the two variables. The scatter diagram would contain points that all lie on a line with a negative slope. C. When the linear correlation coefficient is 1, there is a perfect positive linear relation between the two variables. The scatter diagram would contain points that all lie on a line with a positive slope. D. When the linear correlation coefficient is 1, there is no linear relation between the variables. The scatter diagram would contain points that show no discernable relationship.
B
What does it mean when a part of the population is under-represented? Choose the correct answer below. A. A part of the population is under-represented when their answers on a survey tend not to reflect their true feelings. B. A part of the population is under-represented when it is proportionally smaller in a sample than in its population. C. A part of the population is under-represented when it is proportionally smaller in its population than in a sample. D. A part of the population is under-represented when individuals selected to be in the sample who do not respond to the survey have different opinions from those who do.
c
What does it mean when an observational study is prospective? A. A prospective study is a list of all individuals in a population along with certain characteristics of each individual. B. A prospective study requires that individuals look back in time or require the researcher to look at existing records. C. A prospective study collects the data over time.
B
What does it mean when an observational study is prospective? A. A prospective study requires that individuals look back in time or require the researcher to look at existing records. B. A prospective study collects the data over time. C. A prospective study is a list of all individuals in a population along with certain characteristics of each individual.
c
What does it mean when an observational study is retrospective? A. A retrospective study is a list of all individuals in a population along with certain characteristics of each individual. B. A retrospective study collects the data over time. C. A retrospective study requires that individuals look back in time or require the researcher to look at existing records.
D
What does it mean when sampling is done without replacement? Choose the correct answer below. A. Once a sample is taken, those individuals are no longer considered part of the population. B. Once an individual is selected, the individual can be selected again. C. Once a sample is taken, those individuals cannot be selected for any other samples. D. Once an individual is selected, the individual cannot be selected again.
a
What is a Pareto chart? A. A Pareto chart is a bar graph whose bars are drawn in decreasing order of frequency or relative frequency. B. A Pareto chart is a display of two data sets side by side where the height of each rectangle represents the category's frequency or relative frequency. C. A Pareto chart is a combination of a pie chart and a bar graph.
a
What is a bar graph? A. A bar graph is a horizontal or vertical representation of the frequency or relative frequency of the categories. The height of each rectangle represents the category's frequency or relative frequency. B. A bar graph is a circular graph that uses bars to divide it into segments corresponding to each category. The segments are proportional to the frequency of its category. C. A bar graph represents the frequencies of values either from left-to-right or right-to-left. The different segments of the bar are used to indicate the different frequencies of each category.
C
What is a closed question? What is an open question? A. A closed question has many correct answers, whereas an open question has only one correct answer. B. A closed question is a free-response question, whereas an open question has fixed choices for answers. C. A closed question has fixed choices for answers, whereas an open question is a free-response question. D. A closed question always has yes or no answers, whereas an open question is a free-response question.
A
What is a confounding variable? A. 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. B. A confounding variable is the explanatory variable on which a study has been focused. C. A confounding variable is a response variable that was not considered in a study whose effect cannot be distinguished from a second explanatory variable in the study. D. A confounding variable is a response variable that has an effect on the explanatory variable, but it cannot be accurately measured in the study.
C
What is a lurking variable? A. A lurking variable is a response variable that was not considered in a study, but is also affected by the casual relationship of the explanatory variables in the study. In addition, lurking variables are typically related to response variables in the study. B. A lurking variable is a quantitative variable that has an infinite number of possible values that are not countable. In addition, lurking variables are typically very large numbers that make them difficult, if not impossible, to include in a study. C. 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. D. A lurking variable is a quantitative variable that has either a finite number of possible values or a countable number of possible values. In addition, lurking variables are typically equal to zero, or almost equal to zero.
b
What is an ogive? Choose the correct answer below. A. A bar graph whose bars are drawn in decreasing order of frequency or relative frequency B. A graph that represents the cumulative frequency or cumulative relative frequency for the class C. A graph that uses points, connected by line segments, to represent the frequency or relative frequency for each class D. A circle divided into sectors, each sector representing a category of data
D
What is a case-control study? Choose the correct answer below. A. Case-control studies first identify a group of individuals to participate in the study. These individuals are then observed over a period of time. Over this period of time, characteristics about the individual are recorded. B. Case-control studies are a list of all individuals in a population along with certain characteristics of each individual. C. Case-control studies are observational studies that collect information about individuals at a specific point in time or over a very short period of time. D. 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.
C
What is a cross-sectional study? Choose the correct answer below. A. Cross-sectional studies first identify a group of individuals to participate in the study. These individuals are then observed over a period of time. Over this period of time, characteristics about the individual are recorded. B. Cross-sectional 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. C. 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. D. Cross-sectional studies are a list of all individuals in a population along with certain characteristics of each individual.
A
What is a frame? Choose the correct answer below. A. A frame is a list of the individuals in the population being studied. B. A frame is a list of the individuals in the sample being studied. C. A frame is the population being studied. D. A frame is the sample taken from the population being studied.
A
What is a residual? What does it mean when a residual is positive? Choose the correct answer below. A. A residual is the difference between an observed value of the response variable y and the predicted value of y. If it is positive, then the observed value is greater than the predicted value. B. A residual is the difference between an observed value of the response variable y and the value of the corresponding explanatory variable x. If it is positive, then the response variable is greater than the explanatory variable. C. A residual is the difference between an observed value of the response variable y and the average value of the response variable. If it is positive, then the response variable is greater than the mean. D. A residual is a data point that does not fit the pattern of the rest of the data. If it is positive, then the data point should still be included in the data set.
B
What is meant by confounding? A. Confounding in a study occurs when a single explanatory variable has a great effect on a response variable. This sometimes causes a misleading interpretation of the relationship between the two variables. B. 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. C. Confounding in a study occurs when there is little or no actual relationship between the explanatory and response variable other than random chance. This sometimes causes completely unrelated variables to appear to have a causal relationship, and can cause variables that have almost no relationship to have a very strong relationship. D. Confounding in a study occurs when the effects of the explanatory variable are caused, in some part, by the effects of the response variable. When there is zero confounding in a study, the effects of the response variable are entirely caused by the effects of the explanatory variable.
D
What is replication in an experiment? Choose the correct answer below. A. Replication is randomly assigning each experimental unit to a treatment. B. Replication is grouping together similar experimental units and then using random assignment. C. Replication is pairing up related experimental units. D. Replication is applying each treatment to more than one experimental unit.
B
What is true of the coefficient of variation? A. The coefficient of variation is best used when comparing two data sets that use the same units of measure. B. When converting units of measure, the coefficient of variation is unchanged. C. The coefficient of variation does not give as accurate a measurement as the standard deviation. D. The coefficient of variation is always more meaningful than the standard deviation.
quantitative variable
What type of variable is required when drawing a time-series plot? Why do we draw time-series plots? A __________ is required when drawing a time-series plot.
B
Which is the superior observational study? Why? Choose the correct answer below. A. Cross-sectional studies are always the superior observational study because they are cheap and quick to do. B. Neither study is always the superior to the other. Both have advantages and disadvantages that depend on the situation. C. Case-control studies are always the superior observational study because they are relatively inexpensive to conduct and can be done relatively quickly.
B
Which sampling method does not require a frame? Choose the correct answer below. A. Simple random B. Systematic C. Cluster D. Stratified E. All of the above sampling methods require a frame
A
Why is it important to rotate the two choices presented in the question? Which of the following is correct? A. The choices need to be rotated to minimize response biases. B. The choices need to be rotated to minimize interviewer error. C. The choices need to be rotated to minimize nonresponses. D. The choices need to be rotated to minimize the effect of a poorly worded question.
case control
_____ ______ studies are retrospective studies, meaning that they require individuals to look back in time or require the researcher to look at existing records. In case-control studies, individuals who have a certain characteristic may be matched with those who do not.
classes
________ are the categories by which data are grouped.
symmetric
________ if the median and mean are equal
inferential
________ statistics uses methods that generalize results obtained from a sample to the population and measure the reliability of the results.
Descriptive
_________ statistics consists of organizing and summarizing information collected
completely randomized
__________ ________ design is one in which each experimental unit is randomly assigned to a treatment.
randomized block
__________ _________design is used when the experimental units are divided into homogeneous groups called blocks. Within each block, the experimental units are randomly assigned to treatments.
parameter
a _______ is a numerical summary of a population
stratified sample
a ________ is obtained by dividing the population into homogeneous groups and randomly selecting individuals from each group.
proportion
a relative frequency distribution lists the __________ of occurrences of each category of data.
blocking
grouping together similar experimental units and then randomly assigning the experimental units within each group to a treatment is called
matched pairs design
is an experimental design in which the experimental units are paired up. The pairs are matched up so that they are somehow related (that is, the same person before and after a treatment, twins, husband and wife, same geographical location, and so on). There are only two levels of treatment in a matched-pairs design.
right
skewed ______ if the median is less than the mean
B
to estimate the percentage of defects in a recent manufacturing batch, a quality control manager at IBM selects every 16th computer that comes off the assembly line starting with the seventh until she obtains a sample of 140 computers A. Convenience B. Systematic C. Simple random D. Cluster E. Stratified
B
(d) In the report, the researchers stated, "These results remain significant after adjustment for socioeconomic status." What does this mean? A. It means that socioeconomic status is an explanatory variable and that including this variable in the study changes the results of the study. B. The researchers made an effort to avoid confounding by accounting for potential lurking variables. C. It means that socioeconomic status is not an explanatory variable and that including this variable in the study does not change the results of the study. D. It means that when the results are separated by socioeconomic status, there are significant differences between each socioeconomic status.
statistic
A(n) ________ is a numerical summary of a sample.
cluster sample
A_______ is obtained by dividing the population into groups and selecting all individuals from within a random sample of the groups.