3GFFIRS 11/28/2012 15:43:56 Page2 3GFFIRS 11/28/2012 15:43:56 Page1 TENTH EDITION BIOSTATISTICS A Foundation for Analysis in the Health Sciences 3GFFIRS 11/28/2012 15:43:56 Page2 3GFFIRS 11/28/2012 15:43:56 Page3 TENTH EDITION BIOSTATISTICS A Foundation for Analysis in the Health Sciences WAYNE W. DANIEL, PH.D. Professor Emeritus GeorgiaState University CHAD L. CROSS, PH.D., PSTAT(cid:1)R Statistician Office ofInformatics and Analytics VeteransHealthAdministration Associate Graduate Faculty UniversityofNevada, LasVegas 3GFFIRS 11/28/2012 15:43:56 Page4 VP&EXECUTIVEPUBLISHER: LaurieRosatone ACQUISITIONSEDITOR: ShannonCorliss PROJECTEDITOR: EllenKeohane MARKETINGMANAGER: MelanieKurkjian MARKETINGASSISTANT: PatrickFlatley PHOTOEDITOR: SheenaGoldstein DESIGNER: KenjiNgieng PRODUCTIONMANAGEMENTSERVICES: ThomsonDigital ASSOCIATEPRODUCTIONMANAGER: JoycePoh PRODUCTIONEDITOR: JoleneLing COVERPHOTOCREDIT: #ktsimage/iStockphoto Thisbookwassetin10/12pt,TimesRomanbyThomsonDigitalandprintedandboundbyEdwardsBrothersMalloy. ThecoverwasprintedbyEdwardsBrothersMalloy. Thisbookisprintedonacidfreepaper.(cid:1)1 Foundedin1807,JohnWiley&Sons,Inc.hasbeenavaluedsourceofknowledgeandunderstandingformore than200years,helpingpeoplearoundtheworldmeettheirneedsandfulfilltheiraspirations.Ourcompanyis builtonafoundationofprinciplesthatincluderesponsibilitytothecommunitiesweserveandwhereweliveand work.In2008,welaunchedaCorporateCitizenshipInitiative,aglobalefforttoaddresstheenvironmental, social,economic,andethicalchallengeswefaceinourbusiness.Amongtheissuesweareaddressingarecarbon impact,paperspecificationsandprocurement,ethicalconductwithinourbusinessandamongourvendors,and community and charitable support. For more information, please visit our website: www.wiley.com/go/ citizenship. Copyright#2013,2009,2005,1999JohnWiley&Sons,Inc.Allrightsreserved. Nopartofthispublication maybereproduced,storedinaretrievalsystemortransmittedinanyformorbyanymeans,electronic, mechanical,photocopying,recording,scanningorotherwise,exceptaspermittedunderSections107or108of the1976UnitedStatesCopyrightAct,withouteitherthepriorwrittenpermissionofthePublisher,or authorizationthroughpaymentoftheappropriateper-copyfeetotheCopyrightClearanceCenter,Inc.222 Rosewood Drive, Danvers, MA 01923, website www.copyright.com. Requests to the Publisher for permission shouldbeaddressedtothePermissionsDepartment,JohnWiley&Sons,Inc.,111RiverStreet,Hoboken,NJ 07030-5774, (201)748-6011, fax (201)748-6008, website http://www.wiley.com/go/permissions. Evaluationcopiesareprovidedtoqualifiedacademicsandprofessionalsforreviewpurposesonly,foruseintheir coursesduringthenextacademicyear.Thesecopiesarelicensedandmaynotbesoldortransferredtoathird party.Uponcompletionofthereviewperiod,pleasereturntheevaluationcopytoWiley.Returninstructionsand a free of charge return mailing label are available at www.wiley.com/go/returnlabel. If you have chosen to adopt thistextbookforuseinyourcourse,pleaseacceptthisbookasyourcomplimentarydeskcopy.Outsideofthe UnitedStates,pleasecontactyourlocalsalesrepresentative. LibraryofCongressCataloging-in-PublicationData Daniel,WayneW.,1929- Biostatistics:afoundationforanalysisinthehealthsciences/WayneW. Daniel,ChadLeeCross.—Tenthedition. pagescm Includesindex. ISBN978-1-118-30279-8(cloth) 1. Medicalstatistics. 2. Biometry. I. Cross,ChadLee,1971- II. Title. RA409.D352013 610.7207—dc23 2012038459 PrintedintheUnitedStatesofAmerica 10 9 8 7 6 5 4 3 2 1 3GFFIRS 11/28/2012 15:43:56 Page5 Dr.Daniel Tomychildren,Jean,Carolyn, andJohn,andtothememoryof theirmother,mywife,Mary. Dr.Cross TomywifePamela andtomychildren,AnnabellaGrace andBreannaFaith. 3GFFIRS 11/28/2012 15:43:56 Page6 3GFPREF 11/08/2012 1:59:19 Page7 PREFACE This 10th edition of Biostatistics: A Foundation for Analysis in the Health Sciences was preparedwiththeobjectiveofappealingtoawideaudience.Previouseditionsofthebook have been used by the authors and their colleagues in a variety of contexts. For under- graduates,thiseditionshouldprovideanintroductiontostatisticalconceptsforstudentsin thebiosciences,healthsciences,andformathematicsmajorsdesiringexposuretoapplied statistical concepts. Like its predecessors, this edition is designed to meet the needs of beginninggraduatestudentsinvariousfieldssuchasnursing,appliedsciences,andpublic health who are seeking a strong foundation in quantitative methods. For professionals already working in the health field, this edition can serve as a useful desk reference. Thebreadthofcoverageprovidedinthistext,alongwiththehundredsofpractical exercises, allow instructors extensive flexibility in designing courses at many levels. To thatend,weofferbelowsomeideasontopicalcoveragethatwehavefoundtobeusefulin the classroom setting. Likethepreviouseditionsofthisbook,thiseditionrequiresfewmathematicalpre- requisitesbeyondasolidproficiencyincollegealgebra.Wehavemaintainedanemphasis onpracticalandintuitiveunderstandingofprinciplesratherthanonabstractconceptsthat underliesomemethods,andthatrequiregreatermathematicalsophistication.Withthatin mind,wehavemaintainedarelianceonproblemsetsandexamplestakendirectlyfromthe healthsciencesliteratureinsteadofcontrivedexamples.Webelievethatthismakesthetext moreinteresting for students, and more practical for practicing healthprofessionals who reference the text while performing their work duties. For most of the examples and statistical techniques covered in this edition, we discuss the use of computer software for calculations. Experience has informed our decisiontoincludeexampleprintoutsfromavarietyofstatisticalsoftwareinthisedition (e.g., MINITAB, SAS, SPSS, and R). We feel that the inclusion of examples from these particular packages, which are generally the most commonly utilized by practitioners, provides a rich presentation of the material and allows the student the opportunity to appreciate the various technologies used by practicing statisticians. CHANGESANDUPDATESTOTHISEDITION Themajorityofthechaptersincludecorrectionsandclarificationsthatenhancethematerial that is presented and make it more readable and accessible to the audience. We did, however, make several specific changes and improvements that we believe are valuable contributions tothisedition,andwe thankthe reviewers ofthe previous editionfor their comments and suggestions in that regard. vii 3GFPREF 11/08/2012 1:59:19 Page8 viii PREFACE Specific changes to this edition include additional text concerning measures of dispersioninChapter2,additionaltextandexamplesusingprogramRinChapter6,anew introduction to linear models in Chapter 8 that ties together the regression and ANOVA concepts in Chapters 8–11, the addition of two-factor repeated measures ANOVA in Chapter 8, a discussion of the similarities of ANOVA and regression in Chapter 11, and extensive new text and examples on testing the fit of logistic regression models in Chapter 11. MostimportanttothisneweditionisanewChapter14onSurvivalAnalysis.This newchapterwasborneoutofrequestsfromreviewersofthetextandfromtheexperience oftheauthorsintermsofthegrowing useofthese methodsinapplied research.In this newchapter,weincludedsomeofthematerialfoundinChapter12inpreviouseditions, and added extensive material and examples. We provide introductory coverage of censoring, Kaplan–Meier estimates, methods for comparing survival curves, and the Cox Regression Proportional Hazards model. Owing to this new material, we elected to move the contents of the vital statistics chapter to a new Chapter 15 and make it avai labl e o nl ine (w ww. wi ley. com/colleg e/ daniel). COURSECOVERAGEIDEAS In the table below we provide some suggestions for topical coverage in a variety of contexts,with“X”indicatingthosechapterswebelievearemostrelevantforavarietyof coursesforwhichthistextisappropriate.Thetexthasbeendesignedtobeflexibleinorder to accommodate various teaching styles and various course presentations. Although the textisdesignedwithprogressivepresentationofconceptsinmind,certainofthetopicsmay be skipped or covered briefly so that focus can be placed on concepts important to instructors. Course Chapters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Undergraduatecourseforhealth X X X X X X X X X O O X O O O sciencesstudents Undergraduatecoursein X O O O X X X X X X O X X X O appliedstatisticsfor mathematicsmajors Firstbiostatisticscoursefor X X X X X X X X X X O X X X O beginninggraduatestudents Biostatisticscourseforgraduate X O O O O X X X X X X X X X X healthsciencesstudentswho havecompletedanintroductory statisticscourse X: Suggestedcoverage;O: Optional coverage.