Question

Graded Homework Assignment 1​​​​​​​Unit 1 – Lessons 1 and 2

1. Athletes’ salaries. Here is a small part of a data set that describes Major League Baseball players as of opening day of the 2011 season:

(a) What individuals does this data set describe?

(b) In addition to the player’s name, how many variables does the data set contain? Which of these variables take numerical values? Which of the variables are not numerical variables?

(c) What do you think are the units in which each of the numerical variable salary is expressed? For example, what does it mean to give Josh Beckett’s annual salary as 17,000? (Hint: The average annual salary of a Major League Baseball player on opening day, 2011, was $3,305,393.)

2. Sampling moms. Pregnant and breast-feeding women should eat at least 12 ounces of fish and seafood per week to ensure their babies’ optimal brain development, according to a coalition of top scientists from private groups and federal agencies. A nutritionist wants to know whether pregnant women are eating at least 12 ounces of fish per week. To do so, she obtains a list of the 340 members of a local chain of prenatal fitness clubs and mails a questionnaire to 60 of these women selected at random. Only 21 questionnaires are returned.

(a) What is the variable measured in this study? __________________________________________________

(b) What is the population in this study? ________________________________________________________

(c) What is the sample from which information is actually obtained? _________________________________

(d) What percentage of the women whom the nutritionist tried to contact responded? ____________________

(e) Is this an observational study or an experiment? _______________________________________________

3. Oatmeal and cholesterol. Does eating oatmeal reduce the level of bad cholesterol (LDL)? Here are two ways to study this question.

1. A researcher finds 500 adults over 40 who regularly eat oatmeal or products made from oatmeal. She matches each with a similar adult who does not regularly eat oatmeal or products made from oatmeal. She measures the bad cholesterol (LDL) for each adult and compares both groups.

2. Another researcher finds 1000 adults over 40 who do not regularly eat oatmeal or products made from oatmeal and are willing to participate in a study. She randomly assigns 500 of these to a diet that includes a daily breakfast of oatmeal. The other 500 continue their usual habits. After 6 months, she compares changes in LDL levels.

(a) One of these studies is an observational study and the other is an experiment. Identify with study it the experiment and which study is the observational study and explain why for each.

​Study 1: ​Observational Study​​Experiment

Explanation:

​Study 2: ​Observational Study​​Experiment

Explanation:

(b) Why does the experiment give more useful information about whether oatmeal reduces LDL?

4. Choose your study type. What is the best way to answer each of the questions below: an experiment, a sample survey, or an observational study that is not a sample survey? Explain your choices.

(a) Is your school’s basketball team called for fewer fouls in home games than in away games?

(b) Are college students satisfied with the quality of recreational facilities available to them?

(c) Do college students who have access to audio recordings of course lectures perform better in the course than those who don’t?

5. Choose your study purpose. Give an example of a question about college students, their behavior, or their opinions that would best be answered by

(a) a sample survey.

(b) an observational study that is not a sample survey.

(c) an experiment.

6. Definitions. What is the difference between a census and a sample survey?

7. Instant opinion. On March 29, 2007, BusinessWeek ran an online poll on their Web site and asked readers the question “Do you think Google is too powerful?” Readers clicked on one of three buttons (“Yes,” “No,” or “Not sure”) to vote. In all, 1336 (35.9%) said “Yes,” 2051 (55.1%) said “No,” and 335 (9.0%) said “Not sure.”

(a) What is the sample size for this poll? ___________________________________________

(b) At the Web site, BusinessWeek includes the following statement about its online poll. “Note: These are surveys, not scientific polls.” Explain why the poll may give unreliable information.

(c) Just above the poll question was the following statement: “Google’s accelerating lead in search and its moves into software and traditional advertising are sparking a backlash among rivals.” How might this statement affect the poll results?

8. Ann Landers takes a sample. Advice columnist Ann Landers once asked her divorced readers whether they regretted their decision to divorce. She received approximately 30,000 responses, about 23,000 of which came from women. Nearly 75% said they were glad they divorced, and most of them said they wished they had done it sooner. Explain why this sample is certainly biased. What is the likely direction of the bias? That is, is 75% probably higher or lower than the truth about the population of all adults who have been divorced?

9. A call-in opinion poll. In 2005 the San Francisco Bay Times reported on a poll in New Zealand that found that New Zealanders opposed the nation’s new gay-inclusive civil-unions law by a 3-1 ratio, that is, New Zealanders opposed the law by a margin of 75% to 25%.. This poll was a call-in poll that cost $1 to participate in. The San Francisco Bay Times article also reported that a scientific polling organization found that New Zealanders favor the law by a margin of 56.4% to 39.3%. Explain to someone who knows no statistics why the two polls can give such widely differing results and which poll is likely to be more reliable.

10. Choose an SRS. A firm wants to understand the attitudes of its minority managers toward its system for assessing management performance. Below is a list of all the firm’s managers who are members of minority groups. Use Table A at line 134 to choose 6 to be interviewed in detail about the performance appraisal system.

01

Berliner

09

Hans

17

Liu

25

Rumsey

02

Browne

10

Herbei

18

MacEachern

26

Shantner

03

Calder

11

Holloman

19

Niller

27

Shi

04

Craigmile

12

Hsu

20

Nagaraja

28

Stasny

05

Cressie

13

Kaizar

21

Notz

29

Turkmen

06

Critchlow

14

Kubatko

22

Ozturk

30

Verducci

07

Dean

15

Lee

23

Pearl

31

Wolfe

08

Goel

16

Lin

24

Peruggia

32

Xu

SRS: ________________________________________________________________________

______________________________________________________________________________

11. An election day sample. You want to choose an SRS of 20 of a city’s 480 voting precincts for special voting-fraud surveillance on election day.

(a) Explain clearly how you would label the 480 precincts. How many digits make up each of your labels? What is the greatest number of precincts you could label using this number of digits?

(b) Use Table A to choose the SRS, and list the labels of the precincts you selected. Enter Table A at line 107.

Labels for the twenty precincts selected:

12. Apartment living. You are planning a report on apartment living in a college town. You decide to select three apartment complexes at random for in-depth interviews with residents. Use Table A, starting at line 121, to select a simple random sample of three of the following apartment complexes.

01

Albany Commons

13

Gaslight Village

25

Oak Run

02

Apple Run

14

Georgetowne

26

Old Nantucket

03

Bexley Court

15

Golf Pointe

27

Parliament Ridge

04

Brooks Edge

16

Hickory Mill

28

Pheasant Run

05

Canterbury Way

17

Highview Place

29

Ravine Bluff

06

Chablis Villas

18

Indian Creek

30

Rocky Creek

07

Cherryblossom Way

19

Jefferson Commons

31

Scioto Commons

08

Dublin Plaza

20

Kenbrook Village

32

Stratford East

09

English Village

21

Lawn Manor

33

Timbercreek

10

Fairway Lakes

22

Little Brook Place

34

Walnut Knolls

11

Forest Creek

23

Marble Cliff

35

Woodland Trace

12

Forest Park

24

Morse Glen

36

York Terrace

SRS: ___________________________________________________________________________

________________________________________________________________________________

TABLE A Random digits

Line

101 ​19223 ​95034 ​05756 ​28713 ​96409 ​12531 ​42544 ​82853

102 ​73676 ​47150 ​99400 ​01927 ​27754 ​42648 ​82425 ​36290

103 ​45467 ​71709 ​77558 ​00095 ​32863 ​29485 ​82226 ​90056

104 ​52711 ​38889 ​93074​60227 ​40011 ​85848 ​48767 ​52573

105 ​95592 ​94007 ​69971​91481 ​60779 ​53791 ​17297 ​59335

106 ​68417 ​35013 ​15529​72765 ​85089 ​57067 ​50211 ​47487

107 ​82739 ​57890 ​20807​47511 ​81676 ​55300 ​94383 ​14893

108 ​60940 ​72024 ​17868​24943 ​61790 ​90656 ​87964 ​18883

109 ​36009 ​19365 ​15412​39638 ​85453 ​46816 ​83485 ​41979

110 ​38448 ​48789 ​18338 ​24697 ​39364 ​42006 ​76688 ​08708

111 ​81486 ​69487 ​60513 ​09297 ​00412 ​71238 ​27649 ​39950

112 ​59636 ​88804 ​04634 ​71197 ​19352 ​73089 ​84898 ​45785

113 ​62568 ​70206 ​40325 ​03699 ​71080 ​22553 ​11486 ​11776

114 ​45149 ​32992 ​75730 ​66280 ​03819 ​56202 ​02938 ​70915

115 ​61041 ​77684 ​94322 ​24709 ​73698 ​14526 ​31893 ​32592

116 ​14459 ​26056 ​31424 ​80371 ​65103 ​62253 ​50490 ​61181

117 ​38167 ​98532 ​62183 ​70632 ​23417 ​26185 ​41448 ​75532

118 ​73190 ​32533 ​04470 ​29669 ​84407 ​90785 ​65956 ​86382

119 ​95857 ​07118 ​87664 ​92099 ​58806 ​66979 ​98624 ​84826

120 ​35476 ​55972 ​39421 ​65850 ​04266 ​35435 ​43742 ​11937

121 ​71487 ​09984 ​29077 ​14863 ​61683 ​47052 ​62224 ​51025

122 ​13873 ​81598 ​95052 ​90908 ​73592 ​75186 ​87136 ​95761

123 ​54580 ​81507 ​27102 ​56027 ​55892 ​33063 ​41842 ​81868

124 ​71035 ​09001 ​43367 ​49497 ​72719 ​96758 ​27611 ​91596

125 ​96746 ​12149 ​37823 ​71868 ​18442 ​35119 ​62103 ​39244

126 ​96927 ​19931 ​36089 ​74192 ​77567 ​88741 ​48409 ​41903

127 ​43909 ​99477 ​25330 ​64359 ​40085 ​16925 ​85117 ​36071

128 ​15689 ​14227 ​06565 ​14374 ​13352 ​49367 ​81982 ​87209

129 ​36759 ​58984 ​68288 ​22913 ​18638 ​54303 ​00795 ​08727

130 ​69051 ​64817 ​87174 ​09517 ​84534 ​06489 ​87201 ​97245

131 ​05007 ​16632 ​81194 ​14873 ​04197 ​85576 ​45195 ​96565

132 ​68732 ​55259 ​84292 ​08796 ​43165 ​93739 ​31685 ​97150

133 ​45740 ​41807 ​65561 ​33302 ​07051 ​93623 ​18132 ​09547

134 ​27816 ​78416 ​18329 ​21337 ​35213 ​37741 ​04312 ​68508

135 ​66925 ​55658 ​39100 ​78458 ​11206 ​19876 ​87151 ​31260

136 ​08421 ​44753 ​77377 ​28744 ​75592 ​08563 ​79140 ​92454

137 ​53645 ​66812 ​61421 ​47836 ​12609 ​15373 ​98481 ​14592

138 ​66831 ​68908 ​40772 ​21558 ​47781 ​33586 ​79177 ​06928

139 ​55588 ​99404 ​70708 ​41098 ​43563 ​56934 ​48394 ​51719

140 ​12975 ​13258 ​13048 ​45144 ​72321 ​81940 ​00360 ​02428

141 ​96767 ​35964 ​23822 ​96012 ​94591 ​65194 ​50842 ​53372

142 ​72829 ​50232 ​97892 ​63408 ​77919 ​44575 ​24870 ​04178

143 ​88565 ​42628 ​17797 ​49376 ​61762 ​16953 ​88604 ​12724

144 ​62964 ​88145 ​83083 ​69453 ​46109 ​59505 ​69680 ​00900

145 ​19687 ​12633 ​57857 ​95806 ​09931 ​02150 ​43163 ​58636

146 ​37609 ​59057 ​66967 ​83401 ​60705 ​02384 ​90597 ​93600

147 ​54973 ​86278 ​88737 ​74351 ​47500 ​84552 ​19909 ​67181

148 ​00694 ​05977 ​19664 ​65441 ​20903 ​62371 ​22725 ​53340

149 ​71546 ​05233 ​53946 ​68743 ​72460 ​27601 ​45403 ​88692

150 ​07511 ​88915 ​41267 ​16853 ​84569 ​79367 ​32337 ​03316

Answer 1

Answer: ---- Date: ----08/02/2019

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