PECK, STATISTICS: LEARNING FROM DATA 3

Solution and Answer Guide: Peck, Statistics: Learning From Data 3rd Edition, 9780357758298 1 © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.Solution and Answer Guide

PECK, STATISTICS: LEARNING FROM DATA 3

RD

EDITION, 9780357758298

CHAPTER 01: COLLECTING DATA IN REASONABLE WAYS

TABLE OF CONTENTS

Section 1.2 ............................................................................................................................ 1 Exercise Set 1 ............................................................................................................................. 1 Exercise Set 2 ........................................................................................................................... 2 Additional Exercises for Section 1.2 ...................................................................................... 2 Section 1.3 ........................................................................................................................... 3 Exercise Set 1 ............................................................................................................................ 3 Exercise Set 2 ........................................................................................................................... 3 Additional Exercises for Section 1.3 ...................................................................................... 4 Section 1.4 ........................................................................................................................... 5 Exercise Set 1 ............................................................................................................................ 5 Exercise Set 2 ........................................................................................................................... 6 Additional Exercises for Section 1.4 ..................................................................................... 6 Section 1.5 ........................................................................................................................... 7 Exercise Set 1 ............................................................................................................................ 7 Section 1.5 Exercise Set 2 ....................................................................................................... 9 Additional Exercises for Section 1.5 ..................................................................................... 10 End of Section Exercise Solutions ................................................................................... 10

SECTION 1.2

EXERCISE SET 1

1.1: This is an observational study because the person conducting the study merely recorded (based on a survey) whether or not the respondents believe it is “very important” for couples who have who have children together to be married.

1.2: This is an observational study because the researchers analyzed data from hospital emergency departments. No older people were assigned “walking dog” or “not walking dog” treatments.Statistics Learning from Data, 3e Roxy Peck, Catherine Case(Solutions Manual, All Chapters. 100% Original Verified, A+ Grade) 1 / 4

Solution and Answer Guide: Chapter 01: Collecting Data in Reasonable Ways 2 © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

1.3: This is an experiment because the researchers assigned different toddlers to experimental conditions (adult played with/talked to the robot or the adult ignored the robot).

1.4: This is an observational study because the researchers surveyed U.S. adults and drew a conclusion from the survey results; there were no experimental treatments assigned.

1.5: This is an experiment because the researchers assigned study participants to one of three treatment groups (meditation, distraction task, or relaxation technique).

EXERCISE SET 2

1.6: This is an observational study based on results of a survey (no consumers were assigned to different experimental conditions).

1.7: This is an experiment because the participants (diners at full-service restaurants on a college campus) were assigned to different experimental conditions (usual menus or menus with the addition of calorie labels).

1.8: This is an observational study because the researchers collected data using a survey about “cancel culture” and had the respondents explain the term. There was no assignment to different experimental conditions.

1.9: This is an experiment because the researchers assigned study participants to different experimental conditions (garlic supplement group or no garlic supplement group).

1.10: This is an experiment because the researchers assigned the children to different experimental groups (ball behaving as expected and ball behaving in an unexpected way).

ADDITIONAL EXERCISES FOR SECTION 1.2

1.11: This is an observational study because the researchers observed the proportion of patients who got an infection in the two groups (overnight hospitalization or more than one night hospitalization); there was no assignment of subjects to experimental groups.

1.12: This is an experiment because the course professor assigned each discussion group an instructor who taught under a particular gender identity (perceived gender was the experimental treatment).

1.13: This is an experiment because the study participants were assigned to one of the two experimental groups (how much would you pay for the mug or how much would you sell the mug for).

1.14: The study described was an experiment because the study participants were asked either the first or second question (the participants were assigned to one of the two experimental groups). 2 / 4

Solution and Answer Guide: Chapter 01: Collecting Data in Reasonable Ways 3 © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

SECTION 1.3

EXERCISE SET 1

1.15: (a) The group of 857 bicycle fatalities represents a census of the 2018 bicycle fatalities. (b) Because the group of 857 represents a census, the average age of 47 years is a population characteristic.

1.16: The sample is the 100 San Fernando Valley residents, and the population of interest is all San Fernando Valley residents.

1.17: The headline referenced in the previous exercise is not appropriate because the Los Angeles County Metropolitan Transportation Authority only surveyed 100 residents from those who attended a community forum in Van Nuys on a Monday. Residents who could not attend the forum were not included in the survey. The residents who attended the forum are likely those who feel strongly about the issue. As such, it is not appropriate to generalize the survey results to all San Fernando Valley residents. The sample is biased, and we cannot be sure that the results of this survey are representative of the population as a whole. If results from this study are to be reported at all, a more appropriate headline might be “Over two-thirds of those attending a community forum OK with 1-cent transit tax.” 1.18: There are several reasonable approaches. One is described here. Using the list of all students at the school, write their names on identical slips of paper. Thoroughly mix the slips of paper and select 150 slips. The individuals whose names are on the slips of paper constitute the sample.

1.19: (a) The population of interest is all college students. (b) If the researchers want to generalize to all college students, this sample might not be reasonable. For example, although there are students from different majors in the class, it might be that not all majors are represented.Additionally, giving extra credit encourages those students who need the extra credit or those who are interested in the study to participate; those students who don’t need the extra credit or those who don’t care much might not participate. There might be systematic differences between those who need the extra credit and those who don’t. (c) Given that only students in this class were surveyed, the sample is not likely to be representative of the population of interest (all college students). (d) Selection bias is present because the selection method might exclude students in certain majors or those students who don’t need the extra credit.

1.20: This is a stratified sample because the researcher divided the teachers and other professionals who work in schools into five non-overlapping subgroups (strata), and then sampled from each stratum.

EXERCISE SET 2

1.21: The given percentages are statistics, because they were computed from sample data obtained by a survey. 3 / 4

Solution and Answer Guide: Chapter 01: Collecting Data in Reasonable Ways 4 © 2022 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

1.22: The group of soldiers surveyed represents a census. The reported percentage is a population characteristic, because it was computed using data from the entire population of soldiers.

1.23: (a) This is a convenience sample because there was no random selection of a top medical school or an expert within the school. (b) Because there was no random selection of the infectious disease expert, generalization to all doctors is not reasonable.

1.24: There are several reasonable approaches. One is described here. Write the names of all students enrolled at the college on identical slips of paper. Thoroughly mix the slips of paper and select 100 of the slips. The students whose names are on the 100 slips of paper constitute the simple random sample.

1.25: (a) The population of interest is all Arizona drivers. (b) Although the details of the sampling scheme are not presented, there was random selection of AAA Arizona members. Therefore, the sample was selected in a reasonable way. (c) This sample is not representative of the population of interest because only those people who are AAA Arizona members were included in the sample. (d) Selection bias is present because those drivers who are not AAA Arizona members have been excluded from the sample. Nonresponse bias could also be present because there was no indication of how many surveys were not returned.

1.26: This is a cluster sample because all first-year students take the class, a random sample of 20 sections of the classes (the clusters) was taken, and all students within the selected sections were surveyed.

ADDITIONAL EXERCISES FOR SECTION 1.3

1.27: (a) One example of a leading question is “Knowing that there are health problems associated with consuming too much sugar, and that soft drinks contain large amounts of added sugar, should there be a tax on soft drinks to encourage people to consume less?” This leading question states that there are health problems associated with consuming too much sugar, and people might be concerned with their health. (b) A double-barreled question is “How satisfied are you with the food and service at this restaurant?” It would be better to split the bad question into two questions, such as “How satisfied are you with the food at this restaurant” and “How satisfied are you with the service at this restaurant.” 1.28: The chairman does not understand the power of random selection. Random samples tend to reflect the distribution of voters in the population. Although it is possible to obtain a random sample that is not representative of the population, the risk of getting a sample that is not representative of the population does not depend on what fraction of the population is sampled.The random selection process allows us to be confident that the resulting sample will adequately reflect the population, even when the sample consists of only a relatively small fraction of the population.

1.29: One factor that might contribute to these very different results has to do with who uses landlines. Perhaps older Alabama residents, who might be more conservative and Republican

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