April10,2007 13:35 m90-frontmatter-editorial Sheetnumber1 Pagenumberi cyanmagentayellowblack Elementary Statistics Seventh Edition April10,2007 13:35 m90-frontmatter-editorial Sheetnumber2 Pagenumberii cyanmagentayellowblack April10,2007 13:35 m90-frontmatter-editorial Sheetnumber3 Pagenumberiii cyanmagentayellowblack Elementary Statistics Seventh Edition Neil A. Weiss Department of Mathematics and Statistics Arizona State University Biographies by Carol A. Weiss San Francisco Boston New York Cape Town Hong Kong London Madrid Mexico City Montreal Munich Paris Singapore Sydney Tokyo Toronto April10,2007 13:35 m90-frontmatter-editorial Sheetnumber4 Pagenumberiv cyanmagentayellowblack Publisher: GregTobin Editor-in-Chief: DeirdreLynch ProjectEditor: JoanneHa DevelopmentalEditor: LenoreParens AssociateEditors: ElizabethBernardi,SaraOliverGordus SeniorManagingEditor: KarenWernholm ProductionSupervisor: SheilaSpinney SeniorDesigner: BarbaraT.Atkinson PhotoResearcher: BethAnderson DigitalAssetsManager: MarianneGroth MediaProducer: ChristineStavrou SoftwareDevelopment: BobCarroll,MaryDurnwald MarketingManager: PhyllisHubbard MarketingAssistant: CarolineCelano SeniorAuthorSupport/TechnologySpecialist: JoeVetere SeniorPrepressSupervisor: CarolineFell ManufacturingManager: EvelynBeaton MediaBuyer: GinnyMichaud CoverDesign: Night&DayDesign TextDesign: JeanneCalabreseDesign,Inc. ProductionCoordination: WestWords,Inc. Composition: Techsetters,Inc. Illustration: Techsetters,Inc. CoverPhotograph: Fieldofwildflowers©GettyImages Forpermissiontousecopyrightedmaterial,gratefulacknowledgmentismadetothe copyrightholdersonpageC-1,whichisherebymadepartofthiscopyrightpage. Manyofthedesignationsusedbymanufacturersandsellerstodistinguishtheirproductsare claimedastrademarks. Wherethosedesignationsappearinthisbook,andAddison-Wesley wasawareofatrademarkclaim,thedesignationshavebeenprintedininitialcapsorallcaps. LibraryofCongressCataloging-in-PublicationData Weiss,N.A.(NeilA.) Elementarystatistics/NeilA.Weiss;biographiesbyCarolA.Weiss. –7thed. p.cm. Includesindex. ISBN0-321-42209-0 1.Statistics. I.Title. QA276.12.W4452007 519.5–dc22 2006043506 Copyright©2008PearsonEducation,Inc.Allrightsreserved. Nopartofthispublication maybereproduced,storedinaretrievalsystem,ortransmitted,inanyformorbyany means,electronic,mechanical,photocopying,recording,orotherwise,withouttheprior writtenpermissionofthepublisher. PrintedintheUnitedStatesofAmerica. For informationonobtainingpermissionforuseofmaterialinthiswork,pleasesubmita writtenrequesttoPearsonEducation,Inc.,RightsandContractsDepartment,75Arlington Street,Suite300,Boston,MA02116,faxyourrequestto617-848-7074,ore-mailat http://www.pearsoned.com/legal/permissions.htm. 12345678910-DOW-1110090807 April10,2007 13:35 m90-frontmatter-editorial Sheetnumber5 Pagenumberv cyanmagentayellowblack Tomyfather andthememory ofmymother April10,2007 13:35 m90-frontmatter-editorial Sheetnumber6 Pagenumbervi cyanmagentayellowblack About the Author NeilA.WeissreceivedhisPh.D.fromUCLAin1970andsubsequentlyaccepted anassistant-professorpositionatArizonaStateUniversity(ASU),wherehewas ultimatelypromotedtotherankoffullprofessor. Dr.Weisshastaughtstatis- tics, probability, and mathematics—from the freshman level to the advanced graduate level—for more than 30 years. In recognition of his excellence in teaching,hereceivedtheDean’sQualityTeachingAwardfromtheASUCollege ofLiberalArtsandSciences. Dr.Weiss’comprehensiveknowledgeandexperi- enceensuresthathistextsaremathematicallyandstatisticallyaccurate,aswell aspedagogicallysound. Inadditiontohisnumerousresearchpublications,Dr.Weissistheauthorof ACourseinProbability(Addison-Wesley,2006). Hehasalsoauthoredorcoau- thoredbooksinfinitemathematics,statistics,andrealanalysis,andiscurrently workingonanewbookonappliedregressionanalysisandtheanalysisofvari- ance. His texts—well known for their precision, readability, and pedagogical excellence—areusedworldwide. Dr.Weissisapioneeroftheintegrationofstatisticalsoftwareintotextbooks and the classroom, first providing such integration over 20 years ago in the bookIntroductoryStatistics(Addison-Wesley,1982). WeissandAddison-Wesley continuethatpioneeringspirittothisdaywiththeinclusionofsomeofthemost comprehensiveWebsitesinthefield. Inhissparetime,Dr.Weissenjoyswalking,studyingandpracticingmed- itation,andplayinghold’empoker. Heismarriedandhastwosons. April10,2007 13:35 m90-frontmatter-editorial Sheetnumber7 Pagenumbervii cyanmagentayellowblack Contents Preface xi Supplements xxii Technology Resources xxiii Data Sources xxiv Part I Introduction 1 Chapter 1 The Nature of Statistics 2 CaseStudy: GreatestAmericanScreenLegends 3 1.1 StatisticsBasics 4 1.2 SimpleRandomSampling 12 1.3 OtherSamplingDesigns* 18 1.4 ExperimentalDesigns* 24 ChapterinReview30,ReviewProblems31,FocusingonDataAnalysis34, CaseStudyDiscussion34,Biography35 Part II Descriptive Statistics 37 Chapter 2 Organizing Data 38 CaseStudy: PreventingInfantMortality 39 2.1 VariablesandData 40 2.2 GroupingData 44 2.3 GraphsandCharts 56 2.4 DistributionShapes 72 2.5 MisleadingGraphs 81 ChapterinReview85,ReviewProblems86,FocusingonDataAnalysis90, CaseStudyDiscussion90,Biography91 Chapter 3 Descriptive Measures 92 CaseStudy: TheTripleCrown 93 3.1 MeasuresofCenter 94 3.2 MeasuresofVariation 106 3.3 TheFive-NumberSummary;Boxplots 122 3.4 DescriptiveMeasuresforPopulations;UseofSamples 136 ChapterinReview148,ReviewProblems149,FocusingonDataAnalysis152, CaseStudyDiscussion152,Biography153 vii ∗indicatesoptionalmaterial April10,2007 13:35 m90-frontmatter-editorial Sheetnumber8 Pagenumberviii cyanmagentayellowblack viii Contents Chapter 4 Descriptive Methods in Regression and Correlation 154 CaseStudy: ShoeSizeandHeight 155 4.1 LinearEquationswithOneIndependentVariable 156 4.2 TheRegressionEquation 161 4.3 TheCoefficientofDetermination 177 4.4 LinearCorrelation 186 ChapterinReview196,ReviewProblems197,FocusingonDataAnalysis199, CaseStudyDiscussion199,Biography200 Part III Probability, Random Variables, and Sampling Distributions 201 Chapter 5 Probability and Random Variables 202 CaseStudy: ThePowerball 203 5.1 ProbabilityBasics 204 5.2 Events 212 5.3 SomeRulesofProbability 221 5.4 DiscreteRandomVariablesandProbabilityDistributions* 229 5.5 TheMeanandStandardDeviationofaDiscreteRandomVariable* 237 5.6 TheBinomialDistribution* 243 ChapterinReview260,ReviewProblems260,FocusingonDataAnalysis263, CaseStudyDiscussion264,Biography265 Chapter 6 The Normal Distribution 266 CaseStudy: FootLengthandShoeSizeforWomen 267 6.1 IntroducingNormallyDistributedVariables 268 6.2 AreasUndertheStandardNormalCurve 276 6.3 WorkingwithNormallyDistributedVariables 284 6.4 AssessingNormality;NormalProbabilityPlots 294 ChapterinReview301,ReviewProblems301,FocusingonDataAnalysis304, CaseStudyDiscussion304,Biography305 Chapter 7 The Sampling Distribution of the Sample Mean 306 CaseStudy: TheChesapeakeandOhioFreightStudy 307 7.1 SamplingError;theNeedforSamplingDistributions 308 7.2 TheMeanandStandardDeviationoftheSampleMean 314 7.3 TheSamplingDistributionoftheSampleMean 321 ChapterinReview330,ReviewProblems330,FocusingonDataAnalysis333, CaseStudyDiscussion333,Biography333 ∗indicatesoptionalmaterial April10,2007 13:35 m90-frontmatter-editorial Sheetnumber9 Pagenumberix cyanmagentayellowblack Contents ix Part IV Inferential Statistics 335 Chapter 8 Confidence Intervals for One Population Mean 336 CaseStudy: TheChipsAhoy! 1,000ChipsChallenge 337 8.1 EstimatingaPopulationMean 338 8.2 ConfidenceIntervalsforOnePopulationMeanWhenσ IsKnown 344 8.3 MarginofError 353 8.4 ConfidenceIntervalsforOnePopulationMeanWhenσ IsUnknown 359 ChapterinReview372,ReviewProblems372,FocusingonDataAnalysis376, CaseStudyDiscussion376,Biography377 Chapter 9 Hypothesis Tests for One Population Mean 378 CaseStudy: SexandSenseofDirection 379 9.1 TheNatureofHypothesisTesting 380 9.2 Terms,Errors,andHypotheses 387 9.3 HypothesisTestsforOnePopulationMeanWhenσ IsKnown 396 9.4 P-Values 408 9.5 HypothesisTestsforOnePopulationMeanWhenσ IsUnknown 420 ChapterinReview432,ReviewProblems432,FocusingonDataAnalysis438, CaseStudyDiscussion438,Biography439 Chapter 10 Inferences for Two Population Means 440 CaseStudy: BreastMilkandIQ 441 10.1 TheSamplingDistributionoftheDifferenceBetweenTwoSampleMeansfor IndependentSamples 442 10.2 InferencesforTwoPopulationMeans,UsingIndependentSamples: Standard DeviationsAssumedEqual 448 10.3 InferencesforTwoPopulationMeans,UsingIndependentSamples: Standard DeviationsNotAssumedEqual 462 10.4 InferencesforTwoPopulationMeans,UsingPairedSamples 477 ChapterinReview493,ReviewProblems493,FocusingonDataAnalysis498, CaseStudyDiscussion498,Biography499 Chapter 11 Inferences for Population Proportions 500 CaseStudy: WorldWarIII? 501 11.1 ConfidenceIntervalsforOnePopulationProportion 502 11.2 HypothesisTestsforOnePopulationProportion 514 11.3 InferencesforTwoPopulationProportions 521 ChapterinReview535,ReviewProblems535,FocusingonDataAnalysis538, CaseStudyDiscussion538,Biography538 ∗indicatesoptionalmaterial April10,2007 13:35 m90-frontmatter-editorial Sheetnumber10 Pagenumberx cyanmagentayellowblack x Contents Chapter 12 Chi-Square Procedures 540 CaseStudy: RoadRage 541 12.1 TheChi-SquareDistribution 542 12.2 Chi-SquareGoodness-of-FitTest 543 12.3 ContingencyTables;Association 554 12.4 Chi-SquareIndependenceTest 566 ChapterinReview579,ReviewProblems579,FocusingonDataAnalysis582, CaseStudyDiscussion582,Biography583 Chapter 13 Analysis of Variance (ANOVA) 584 CaseStudy: HeavyDrinkingAmongCollegeStudents 585 13.1 TheF-Distribution 586 13.2 One-WayANOVA:TheLogic 587 13.3 One-WayANOVA:TheProcedure 595 ChapterinReview610,ReviewProblems610,FocusingonDataAnalysis612, CaseStudyDiscussion612,Biography613 Chapter 14 Inferential Methods in Regression and Correlation 614 CaseStudy: ShoeSizeandHeight 615 14.1 TheRegressionModel;AnalysisofResiduals 616 14.2 InferencesfortheSlopeofthePopulationRegressionLine 629 14.3 EstimationandPrediction 637 14.4 InferencesinCorrelation 647 ChapterinReview654,ReviewProblems655,FocusingonDataAnalysis658, CaseStudyDiscussion658,Biography659 Appendixes Appendix A Statistical Tables A-1 Appendix B Answers to Selected Exercises A-27 Index I-1 Photo Credits C-1 ∗indicatesoptionalmaterial