, se V e NTH eDITION g
Essentials of g g
Nursing Research g
Appraising Evidence f g g
or Nursing Practice
g g
D EN I SE F. POLIT, PhD
g g g
President,gHumanalysis,gInc.,gSaratogag Springs,gNewgYork
andgAdjunctgProfessor,gGriffithgUniversitygSchoolgofgNursing,
GoldgCoast,gAustraliag(www.denise
polit.com)
CHERYL TATANO BECK, DNSc, CNM, FAAN
g g g g g
DistinguishedgProfessor,gSchoolgofgNursing,g
UniversitygofgConnecticut
Storrs,gConnecticut
, AcquisitionsgEditor:gHilariegSurrena
Managingg Editor:g HelengKogut
DirectorgofgNursinggProduction:gHelengEwang Se
niorgManaginggEditorg/gProduction:gErikagKorsg
ProductiongEditor:gMarygKinsella
ArtgDirector,gDesign:gJoangWendt
ArtgDirector,gIllustration:gBrettgMcNaughtong Ma
nufacturinggCoordinator:gKaringDuffieldg Product
iongServicesg/gCompositor:gAptara
Seventhg Edition
Copyrightg ©g 2010g Woltersg Kluwerg Healthg |g Lippincottg Williamsg &g Wilkins.
Copyrightg©g2006,g2001gbygLippincottgWilliamsg&gWilkins.gCopyrightg©g1997gbygLippincott–RavengPub-
g lishers.gCopyrightg©g1993,g1989,g1985gbygJ.gB.gLippincottgCompany.gAllgrightsgreserved.gThisgbookgisgpro-
g tectedgbygcopyright.gNogpartgofgthisgbookgmaygbegreproducedgorgtransmittedginganygformgorgbyganygmean
s,g includingg asg photocopiesg org scanned-
ing org otherg electronicg copies,g org utilizedg byg anyg informationg storageg andgretrievalgsystemgwithoutgwritt
engpermissiongfromgthegcopyrightgowner,gexceptgforgbriefgquotationsg embodiedg ing criticalg articlesg andg rev
iews.g Materialsg appearingg ing thisg bookg preparedg byg individualsg asg partg ofg theirg officialg dutiesg asg U.S.g g
overnmentg employeesg areg notg coveredg byg theg above-
mentionedg copyright.g Tog requestg permission,g pleaseg contactg Lippincottg Williamsg &g Wilkinsg atg 530g Wa
lnutg Street,g Philadelphiag PAg19106,(produ
ctsgandgservices).
9g 8g 7g 6g 5g 4g 3g 2g 1
PrintedgingChina
Libraryg ofg Congressg Cataloging-in-Publicationg Data
Polit,gDenisegF.
Essentialsg ofg nursingg researchg :g appraisingg evidenceg forg nursingg practiceg /g Deniseg F.g Polit,g Cherylg
TatanogBeck.g—g7thged.
p.g ;g cm.
Includesgbibliographicalgreferencesgandgindex.
g ISBN-13:g978-0-7817-8153-
4g(alk.gpaper)g ISBN-10:g0-7817-8153-
1g(alk.gpaper)
1.g Nursing—
Research.g I.g Beck,gCherylgTatano.g II.g Title.g [DNLM:g 1.
g NursinggResearch.g WYg20.5gP769egg2008]
RT81.5.P63g 2008
610.73072—dc22 2008047112
Careghasgbeengtakengtogconfirmgthegaccuracygofgtheginformationgpresentedgandgtogdescribeggen-
g erallygacceptedgpractices.gHowever,gthegauthors,geditors,gandgpublishergaregnotgresponsiblegforgerrorsgorg
omissionsg org forg anyg consequencesg fromg applicationg ofg theg informationg ing thisg bookg andg makeg nog w
ar-
g ranty,gexpressedgorgimplied,gwithgrespectgtogthegcurrency,gcompleteness,gorgaccuracygofgthegcontentsgofgth
eg publication.g Applicationg ofg thisg informationg ing ag particularg situationg remainsg theg professionalg resp
onsi-
g bilitygofgthegpractitioner;gthegclinicalgtreatmentsgdescribedgandgrecommendedgmaygnotgbegconsideredg abs
olutegandguniversalgrecommendations.
Thegauthors,geditors,gandgpublisherghavegexertedgeverygeffortgtogensuregthatgdruggselectiongandg
dosageg setg forthg ing thisg textg areg ing accordanceg withg theg currentg recommendationsg andg practiceg atg theg ti
meg ofgpublication.gHowever,gingviewgofgongoinggresearch,gchangesginggovernmentgregulations,gandgthegcon
stantg flowgofginformationgrelatinggtogdruggtherapygandgdruggreactions,gthegreadergisgurgedgtogcheckgthegpa
ckageg insertgforgeachgdruggforganygchangegingindicationsgandgdosagegandgforgaddedgwarningsgandgprecauti
ons.gThisg isg particularlyg importantg wheng theg recommendedg agentg isg ag newg org infrequentlyg employedg
drug.