2. Research Design-LDR 280_2.PPT

8/14/2019 2. Research Design-LDR 280_2.PPT

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LIHAM-PANGANGALAKAL

Ginagamitbilangtransiyunal na

ugnayan ngmga taong nasaloob ng isang

organisasyon.


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Layunin ng LihamLayunin ng Liham

Layunin nito upang mapanatili saLayunin nito upang mapanatili sapakikitungo sa mga kliyente ngpakikitungo sa mga kliyente ngkompanya.kompanya.

Maging daan ng mabilis na paraan ngMaging daan ng mabilis na paraan ngkomunikasyonkomunikasyon

Binigigyan diin dito ang mambabasa.Binigigyan diin dito ang mambabasa.

22


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15 Cs15 CsA. Candid , concrete tuiran, tiyak,matapat

B. Clear ! malina

C. Co"erent may kaisa"an ang mga ideya

#. Common, Con$incing, Cordial

%. Concerned, Concise, Considerate

&. Complete, Con$ersational

G. Correct, Courteous, Credible


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BAHAGI NG LIHAMBAHAGI NG LIHAM

Letter'eadLetter'ead

General #ata (e$icesGeneral #ata (e$ices

2)) Buendian A$e.2)) Buendian A$e.

*el. +o.*el. +o.

&!mail&!mail -etsa-etsa AddressAddress Linya para saLinya para sa

AttensyonAttensyon

(alutation(alutation (ubect Line(ubect Line /ataan/ataan ComlimentaryComlimentary

ClosingClosing CompanyCompany

(ignature(ignature 0riter0riter

dentiicationdentiication


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4eerence nitial4eerence nitial &nclosure 4eminder&nclosure 4eminder

Copy +otationCopy +otation

55


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Methods of ResearchMethods of Research

Descriptive ResearchDescriptive Research

88

Historical ResearchHistorical Research

Experimental ResearchExperimental Research


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! is t"e critical in$estigation o e$ents,de$elopments and e:periences o t"e

past, t"e careul eig"ing o e$idenceo t"e $alidity o sources o inormationon t"e past and t"e interpretation ot"e eig"ed e$idence

Historical Research


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1)1)

Methods of Historical

Research


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1111

a. Classiication o "istorical sources

b. 0"ere t"e sources are located

c. (ystemati;ing your note taking


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a.&:ternal Criticism

b. nternal Criticism

!in$ol$es inding out i t"e source material isgenuine and i it possesses te:tual integrity

!c"eck on t"e meaning and trustort"iness ot"e data it"in t"e documents


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DescriptiveResearch

describes t"e population


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Developing Research

Hypotheses

Intriguing Observation,

Intellectual Curiosity

Defining Research

Problem & Objectives

Testing Hypo!

Data "nalysis &

Interpretation

#ampling Design

Refinement of theory

$In%uctive Reasoning

Data Co%ing,

"n%'%iting

Developing Operational

Definitions for

Research (ariables

)uil%ing the Theoretical

*rame+or an% the

Research -o%el

Data Collection

-ore Careful #tu%ying

of the Phenomenon

THE PROCESS OF

EMPIRICAL RESEARCH

*'& -4=C&(( =% M-&4CAL4&(&A4C'


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Experimental Research

is a study conducted in t"elaboratory. %ield e:periments and>uasi! e:perimental researc" allunder t"is type.


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Questions or Comments

?


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RESEARCH DESIGNRESEARCH DESIGN

CONCLUSION VLIDI!"CONCLUSION VLIDI!"reers to t"e e:tent oreers to t"e e:tent oresearc"er?s ability toresearc"er?s ability to dra accurate conclusionsdra accurate conclusionsrom t"erom t"eresearc". *"at is, t"e degree o a study?sresearc". *"at is, t"e degree o a study?s

a#a# Internal Validit$Internal Validit$@@correctness o conclusionscorrectness o conclusionsregarding t"eregarding t"erelations"ips among $ariablerelations"ips among $ariables e:amineds e:amined0"et"er t"e researc" indings accurately relect "o t"e researc"0"et"er t"e researc" indings accurately relect "o t"e researc"

$ariables are really connected to eac" ot"er.$ariables are really connected to eac" ot"er.

a#a# External Validit$External Validit$Generali;ability o t"eGenerali;ability o t"e indings to t"eindings to t"eintendedappropriate populationsettinintendedappropriate populationsettingg

RESERCH DESI%NRESERCH DESI%N&& TheTheblueprint.roa%mapblueprint.roa%mapthat +ill gui%e thethat +ill gui%e theresearchresearch

The test for theThe test for the /uality of a stu%y0s research %esign/uality of a stu%y0s research %esign is theis the

stu%y0sstu%y0s concl'sion validit$concl'sion validit$..

PR!"SS # $"S%&'%'& ('$ !'$)!*%'& (PR!"SS # $"S%&'%'& ('$ !'$)!*%'& (


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WhatWhat--What was studied?--What was studied? What aboutWhat about--What aspects of--What aspects of

the subject were studied?the subject were studied? What forWhat for--What is/was the--What is/was the

significance of the study?significance of the study?

What did prior lit./research say?What did prior lit./research say?

What was doneWhat was done--How was the--How was the

study conducted?study conducted?

What was found?What was found? So what?So what?

What now?What now?

1. ntroduction,

4esearc" -roblems

=becti$es, ustiication

2. Literature 4e$ie

3. Met"odologyD4esearc" sample, data

collection, measurement, data analysisE

. 4esults #iscussion

5. mplications

6. Conclusions and

4ecommendations or %uture 4esearc"

PR!"SS # $"S%&'%'& ('$ !'$)!*%'& (PR!"SS # $"S%&'%'& ('$ !'$)!*%'& (R"S"(R!H PR+"!*,R"S"(R!H PR+"!*,


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RESEARCH DESIGNRESEARCH DESIGN

F ariance o t"e +#&-&+#&+* #&-&+#&+*ariance o t"e +#&-&+#&+* #&-&+#&+*$ariables D$ariables DS$stematic VarianceS$stematic VarianceEE

F ariability o potential +H(A+C&&I*4A+&=H(ariability o potential +H(A+C&&I*4A+&=H(

C=+%=H+#+G $ariables DC=+%=H+#+G $ariables DConfo'ndin( VarianceConfo'ndin( VarianceEE

F ariance attributable to &44=4 + M&A(H4&M&+*ariance attributable to &44=4 + M&A(H4&M&+*

DDError VarianceError VarianceE.E.

'oJ'oJ

'o do you ac"ie$e'o do you ac"ie$einternal and external validit$internal and external validit$ Di.e.,Di.e.,conclusion $alidityEJconclusion $alidityEJ

By eecti$elyBy eecti$ely controllin( ) t$pes ofcontrollin( ) t$pes of variancesvariances


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!$pes

of DescriptiveResearch

a. (ur$ey. A sur$ey is used"en t"e obecti$es o t"e studyis to see a general speciic

picture o t"e population underin$estigation in terms o t"eirsocial and economic

c"aracteristics


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Effective Research DesignEffective Research Design

MAIMAIimi;e (ystematic arianceimi;e (ystematic ariance

M+M+imi;e &rror arianceimi;e &rror ariance

C=+C=+trol ariance o +uisance&:traneoustrol ariance o +uisance&:traneous&:ogenousConounding $ariables&:ogenousConounding $ariables

Guiding principleGuiding principleor eecti$e control oor eecti$e control o$ariances Dand, t"us, eecti$e researc"$ariances Dand, t"us, eecti$e researc"

designE isdesignE is

*"e*"e MAIM+C=+MAIM+C=+-rinciple-rinciple


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+ &I-&4M&+*(J+ &I-&4M&+*(J

D"ere t"e researc"er actuallyD"ere t"e researc"er actually manipulates t"e independentmanipulates t"e independent

$ariable and measures its impact on t"e dependent $ariableE$ariable and measures its impact on t"e dependent $ariableE -roper manipulation o e:perimental conditions-roper manipulation o e:perimental conditions

to ensure "ig" $ariability in indep. $ar.to ensure "ig" $ariability in indep. $ar.

+ +=+!&I-&4M&+*AL (*H#&(J+ +=+!&I-&4M&+*AL (*H#&(J

D"ere independent and dependent $ariables are measuredD"ere independent and dependent $ariables are measuredsimultaneously and t"e relations"ip beteen t"em aresimultaneously and t"e relations"ip beteen t"em aree:aminedEe:aminedE

Appropriate subect selectionAppropriate subect selectionDselecting subectsDselecting subectst"at are suiciently dierent it" respect to t"et"at are suiciently dierent it" respect to t"e

study?s main $ar.E!!a$oidstudy?s main $ar.E!!a$oid 4ange 4estriction4ange 4estriction

M*M*imi+in( S$stematic Variance&imi+in( S$stematic Variance&

0idening t"e range o $alues0idening t"e range o $alueso researc" $ariables.o researc" $ariables.


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TypesTypes

of Descriptiveof DescriptiveResearchResearch

a.a. (ur$ey(ur$ey. A sur$ey is used "en. A sur$ey is used "ent"e obecti$es o t"e study is tot"e obecti$es o t"e study is to

see a general speciic picture osee a general speciic picture ot"e population undert"e population underin$estigation in terms o t"eirin$estigation in terms o t"eir

social and economicsocial and economicc"aracteristicsc"aracteristics


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So'rces of error variance&So'rces of error variance& -oorly designed measurement instruments-oorly designed measurement instruments

DDinstrumentation errorinstrumentation errorEE

&rror emanating rom study subects De.g.,&rror emanating rom study subects De.g.,response errorresponse errorEE

Conte:tual actorsConte:tual actorst"at reduce a soundaccuratet"at reduce a soundaccuratemeasurement instrument?s capacity to measuremeasurement instrument?s capacity to measureaccurately.accurately.

Ho, to Minimi+e Error Variance-Ho, to Minimi+e Error Variance- ncreasencrease $alidity$alidityandand reliabilityreliabilityoo

measurement instruments.measurement instruments. Measure $ariables under asMeasure $ariables under as idealideal

conditionsconditionsas possible.as possible.

MINMINimi+in( Error Varianceimi+in( Error Variance Dmeasurement errorEDmeasurement errorE Minimi;ingMinimi;ingt"e part o $ariability in scores t"at ist"e part o $ariability in scores t"at is

caused bycaused by error in measurementerror in measurement..


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1 Historical %ata on pollutionan% longevity

2 Relationship bet+een lielihoo% of

hearing problems an% high bloo% pressure

3 Recent stat sho+ in-vitroi%s are 4 times more liely to %evelop eye tumors

$Culprit! in5vitro fathers0 ol%er age&

6 #ignificantly more arme% store robberies %uring the col% +inter %ays 2626


May or may not be o primary interest to t"e researc"er,May or may not be o primary interest to t"e researc"er, But, can produceBut, can produce undesirable $ariationundesirable $ariationin t"e studyKsin t"e studyKs

dependent $ariable, and causedependent $ariable, and cause misleadingmisleadingoror eirdeirdresultsresults *"us, i not controlled,*"us, i not controlled, can contaminatedistort t"e truecan contaminatedistort t"e true

relations"ipDsErelations"ipDsEbeteen t"e independent and dependentbeteen t"e independent and dependent$ariableDsE o interest$ariableDsE o interest

i.e., conounding $ar. can result in ai.e., conounding $ar. can result in a spuriousspurious!! as opposed to!! as opposed tosubstanti$esubstanti$e!!correlation!!correlation beteen and #beteen and #.. &:ampleJ&:ampleJ

Hearing )loo%

Problem Pressure

CO7CO7trolling (ariance of Confoun%ing.7uisance (ariables!trolling (ariance of Confoun%ing.7uisance (ariables!

*IR#T, +hat are*IR#T, +hat are7uisance.Confoun%ing7uisance.Confoun%ing(ariables8(ariables8

Age

Eff ti R h D iEff ti R h D i


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Conducting t"e e:periment in aConducting t"e e:periment in a controlled en$ironmentcontrolled en$ironment De.g.,De.g.,laboratoryE, "ere e canlaboratoryE, "ere e can "old $alues"old $alueso potential conoundingo potential conounding$ariables$ariables constantconstant..

(ubect selection(ubect selectionDe.g., matc"ing subects in e:perimentsEDe.g., matc"ing subects in e:perimentsE 4andom assignment4andom assignmento subects D$ariations o conounding $ariableso subects D$ariations o conounding $ariables

are e$enly distributed beteen t"e e:perimental and control groupsEare e$enly distributed beteen t"e e:perimental and control groupsE

In Survey Resear!"In Survey Resear!" (ample selection(ample selectionDe.g., including only subects it" appropriateDe.g., including only subects it" appropriate

c"aracteristics@usingc"aracteristics@using malemalecollege graduatescollege graduatesas subects ill controlas subects ill controlor potential conounding eects o gender and educationEor potential conounding eects o gender and educationE

Statistical ControlStatistical Control!!!anticipating, measuring, and!anticipating, measuring, and statisticallystatisticallycontrolling or conounding $ariables? eectscontrolling or conounding $ariables? eectsDi.e., "old t"emDi.e., "old t"emstatistically constantstatistically constant, or statistically remo$ing t"eir eectsE., or statistically remo$ing t"eir eectsE.

HO. !O CON!ROL /OR CON/OUNDIN%0HO. !O CON!ROL /OR CON/OUNDIN%0

NUISNCE VRI1LES-NUISNCE VRI1LES-

In E#perimental SettingsIn E#perimental Settings $eg, *ertili9er "mount Rate of Plant :ro+th&$eg, *ertili9er "mount Rate of Plant :ro+th&""#ome Potential Confoun%ing (ariables8#ome Potential Confoun%ing (ariables8


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Correlational Research

in$ol$es t"e collection o to orin$ol$es t"e collection o to ormore sets o data rom a group omore sets o data rom a group o

subects it" t"e attempt tosubects it" t"e attempt todetermine t"e subse>uentdetermine t"e subse>uentrelations"ip beteen t"ose sets orelations"ip beteen t"ose sets odata.data.


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Ex 2ost /acto Research

is a systematic empirical in>uiryin "ic" t"e researc"er does not

"a$e direct control o t"eindependent $ariables.


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Eval'ation Research

udges t"e $alue, ort" or merit

o an e:isting program. %ormati$eor summati$e e$aluation are appliedin training programs, te:tbooks,

manuals or curriculums.


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Ade>uate Dull range oE $ariability in $alues oAde>uate Dull range oE $ariability in $alues oresearc" $ariables,researc" $ariables,

-recise and accurate measurement,-recise and accurate measurement, dentiying and controlling t"e eects odentiying and controlling t"e eects o

conounding $ariables, andconounding $ariables, and Appropriate subect selectionAppropriate subect selection

4&CA-4&CA-&ecti$e researc" design is a unction o J&ecti$e researc" design is a unction o J


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BASIC DESIGNSBASIC DESIGNS

Experimental Desi(ns&Experimental Desi(ns& *rue &:perimental (tudies*rue &:perimental (tudies

-re!e:perimental (tudies-re!e:perimental (tudies

uasi!&:perimental (tudiesuasi!&:perimental (tudies

Non3Experimental Desi(ns&Non3Experimental Desi(ns&

&:post %actoCorrelational (tudies&:post %actoCorrelational (tudies

S2ECI/IC !"2ES O/ RESERCH DESI%N

BA(C 4&(&A4C' #&(G+(


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EXERIMENTA! DESIGNSEXERIMENTA! DESIGNS

RESUL!&RESUL!& (igniicant mpro$ement rom =1 to =2(igniicant mpro$ement rom =1 to =2Di.e., sig. =2 ! =1 dierenceEDi.e., sig. =2 ! =1 dierenceE

4UES!ION&4UES!ION& #id I Dt"e drugE cause t"e#id I Dt"e drugE cause t"eimpro$ementJimpro$ementJ

One of the simplest e;perimental %esigns is the ONE %ROU2 2RE!ES!32OS!!ES! DESI%N33E*M2LE-

One +ay to e;amine 'fficacy of a Drug!

O$ % O&

-easure DR


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'a$e'a$e only s"ononly s"onIN is a (H%%C&+*IN is a (H%%C&+*conditionconditionor t"e c"angeor t"e c"angeONONDi.e., presence o I isDi.e., presence o I isassociated it" a c"ange in OE.associated it" a c"ange in OE.

But,But, is IN also a +&C&((A4Ois IN also a +&C&((A4Ocondition orcondition orOJOJ

'o do you $eriy t"e latterJ'o do you $eriy t"e latterJ By s"oing t"at t"e c"ange ould not "a$eBy s"oing t"at t"e c"ange ould not "a$e

"appened in t"e absence o I@using a"appened in t"e absence o I@using a

C=+*4=L G4=H-.C=+*4=L G4=H-.

'avi( Hume)oul( !ave *een tempte( to say +,ES.

He )as a positivist an( )ante( to iner ausality *ase(

on !ig! orrelations *et)een events.

/ut su! an inerene oul( *e seriously la)e(.

=hy8

Davi% Hume, 1>th

Century #cottish

Philosopher


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C=+*4=L G4=H-C=+*4=L G4=H-simulates absence o Isimulates absence o I =rigin o using Control Groups DA tale rom=rigin o using Control Groups DA tale rom ancient &gyptEancient &gyptE

2retest 2ost3!est2retest 2ost3!est Control %ro'pControl %ro'pDesi(n33Desi(n33(uppose random(uppose random

assignment Dassignment DRRE as used to control conounding $ariablesE as used to control conounding $ariables

RR Exp5 %ro'p O6E * O7EExp5 %ro'p O6E * O7E

RR Ctrl %ro'p O6C O7C Ctrl %ro'p O6C O7C

RESUL!&RESUL!& =2& P =1& =2C +otP =1C=2& P =1& =2C +otP =1C4UES!ION&4UES!ION& #id I cause t"e impro$ement in &:p.#id I cause t"e impro$ement in &:p.

GroupJGroupJ


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+eed+eed proper orm o controlproper orm o [email protected].,@e.g., -lacebo-lacebo..

RR Exp5 %ro'p O6E * O7EExp5 %ro'p O6E * O7E RR Ctrl %ro'p O6C 2lace8o O7CCtrl %ro'p O6C 2lace8o O7C

4UES!ION&4UES!ION& Can e no conclude I caused t"e impro$ementCan e no conclude I caused t"e impro$ementin &:p. GroupJin &:p. GroupJ

0OT 0ECESSARIL,1 2!y not3?Po+er of suggestibility $The Ha+thorne 'ffect&

CO7C@


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Experimental st'diesExperimental st'dies need toneed to controlcontrolforfor potentialpotentialconfo'ndin( factorsconfo'ndin( factorsthat ma$ threaten internal validit$that ma$ threaten internal validit$of the experiment&of the experiment&

Ha,thorne EffectHa,thorne Effect is only one potential conounding actoris only one potential conounding actorin e:perimental studies.in e:perimental studies.

=t"er suc" actors are=t"er suc" actors are

Histor$-Histor$- Biasing e$ents t"at occur beteen pretest and post!testBiasing e$ents t"at occur beteen pretest and post!test

Mat'ration-Mat'ration- -"ysicalbiologicalpsyc"ological c"anges in t"e subects-"ysicalbiologicalpsyc"ological c"anges in t"e subects

!estin(-!estin(- &:posure to pretest inluences scores on post!test&:posure to pretest inluences scores on post!test

Instr'mentation-Instr'mentation- %las in measurement instrumentprocedure%las in measurement instrumentprocedure



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Experimental st'diesExperimental st'diesneed toneed to controlcontrolforfor potentialpotentialconfo'ndin( factorsconfo'ndin( factorsthat ma$ threaten internal validit$that ma$ threaten internal validit$

of the experiment 9Contin'ed#&of the experiment 9Contin'ed#&

Selection-Selection- (ubects in e:perimental control groups dierent rom t"e start(ubects in e:perimental control groups dierent rom t"e start

Statistical Re(ression 9re(ression to,ard the mean#-Statistical Re(ression 9re(ression to,ard the mean#- (ubects selected based on e:treme pretest $alues(ubects selected based on e:treme pretest $alues #isco$ered by#isco$ered by %rancis Galton%rancis Galtonin 1877in 1877

Experimental Mortalit$-Experimental Mortalit$-

#ierential drop!out o subects rom e:perimental and control#ierential drop!out o subects rom e:perimental and controlgroups during t"e studygroups during t"e study

EtcEtc..&:perimental designs mostly used in&:perimental designs mostly used in natural and p"ysicalnatural and p"ysical

sciencessciences..

Generally, "ig"er internal $alidity, loer e:ternalGenerally, "ig"er internal $alidity, loer e:ternal$alidity$alidity


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C"RRE!ATI"NA! DESIGNSC"RRE!ATI"NA! DESIGNS


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*"e design o c"oice in*"e design o c"oice in social sciencessocial sciencessince t"esince t"e p"enomenonp"enomenon

under study is usuallyunder study is usually not reproducible in a laboratory settingnot reproducible in a laboratory setting

4esearc"er "as4esearc"er "as little or no controllittle or no controlo$er study?s indep., dep.o$er study?s indep., dep.and t"eand t"e numerous potentialnumerous potential conounding $ariablesconounding $ariables,,

=ten t"e researc"er=ten t"e researc"er

concomitantly measuresconcomitantly measures

all t"e studyall t"e study

$ariables De.g., independent, dependant, etc.E,$ariables De.g., independent, dependant, etc.E,

*"en e:amines t"e olloing types o relations"ips*"en e:amines t"e olloing types o relations"ips correlations among $ariablescorrelations among $ariablesoror

dierences among groupsdierences among groups,,

nability to controlnability to controlor eects oor eects o conounding $ariablesconounding $ariables makesmakescausal inerencescausal inerencesregarding relations"ips among $ariablesregarding relations"ips among $ariablesmore diicultmore diicultand, t"usand, t"us

Generally, "ig"er e:ternal $alidity, loer internal $alidityGenerally, "ig"er e:ternal $alidity, loer internal $alidity

NON3E*2ERIMEN!L0CORREL!IONL DESI%NSNON3E*2ERIMEN!L0CORREL!IONL DESI%NS



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NO! NECESSRIL": E*M2LES&NO! NECESSRIL": E*M2LES&

.ater /l'oridation and IDS.ater /l'oridation and IDS

99San Francisco ChronicleSan Francisco Chronicle; Sep5 ?#; Sep5 ?#

rmed store ro88eries and cold ,eatherrmed store ro88eries and cold ,eather

Lon(evit$ and 2oll'tionLon(evit$ and 2oll'tion

In3vitro 8irth and li@elihood of developin( e$eIn3vitro 8irth and li@elihood of developin( e$et'morst'mors

Hearin( pro8lem and 8lood press'reHearin( pro8lem and 8lood press're

.hat can a si(nificant correlation mean then-.hat can a si(nificant correlation mean then-

7on5e;perimental %esigns rely on correlational evi%ence

65ESTIO0" Does a significant correlation bet+een t+o

variables in a non5e;perimental stu%y necessarily represent a

causal relationship bet+een those variables8


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C"RRE!ATI"NA! ST#DIESC"RRE!ATI"NA! ST#DIES

a.a. Bot" $ariables are eects o a common cause DorBot" $ariables are eects o a common cause Dor bot"bot"correlated it" a t"ird $ariableE, i.e., spurious correlationcorrelated it" a t"ird $ariableE, i.e., spurious correlationDe.g., air pollution and lie e:pectancy, "earing problem De.g., air pollution and lie e:pectancy, "earing problem blood pressure, country?s annual ice cream sales andblood pressure, country?s annual ice cream sales andre>uency o "ospital admissions or "eat strokeEre>uency o "ospital admissions or "eat strokeE

b.b. Bot" $ar.Bot" $ar. alternati$e indicatorsalternati$e indicatorso same concepto same conceptDe.g., C"urc" attend. %re>. o -raying!!religiosityE.De.g., C"urc" attend. %re>. o -raying!!religiosityE.

c.c. Bot" parts oBot" parts o a common QsystemQ or Qcomple:RQ tend toa common QsystemQ or Qcomple:RQ tend tocome as a packagecome as a packageDe.g., martini drinking and opera attendance!!lie styleEDe.g., martini drinking and opera attendance!!lie styleE

d.d. %ortuitous!!%ortuitous!!Coincidental correlationCoincidental correlation, no logical relations"ip, no logical relations"ip

De.g., =utcome o super bol games and mo$ement o stockDe.g., =utcome o super bol games and mo$ement o stockmarketEmarketE

AT LEAST FO5R OTHER POSSI/LE I0TERPRETATIO0S7REASO0S

FOR CORRELATIO0S /ET2EE0 T2O 8ARIA/LES"



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Covariation R'leCovariation R'leDI and O must beDI and O must becorrelatedE!!+ecessary but not suicient condition.correlatedE!!+ecessary but not suicient condition.

!emporal 2recedence R'le!emporal 2recedence R'leD I is t"e cause, OD I is t"e cause, Os"ould not occur until ater IE.s"ould not occur until ater IE.

Internal Validit$ R'leInternal Validit$ R'leDAlternati$e plausibleDAlternati$e plausiblee:planations o O and I!O relations"ips s"ould bee:planations o O and I!O relations"ips s"ould beruled out Di.e., eliminate ot"er possible causesE.ruled out Di.e., eliminate ot"er possible causesE.

n practice, t"is means e:ercising caution byn practice, t"is means e:ercising caution byidentiying potentialidentiying potential conounding $ariables andconounding $ariables and

2HE0 IS IT SAFER TO I0FER CA5SAL

LI09A:ES FROM STRO0: CORRELATIO0S3;o!n Stuart Mill

Documents

2. Research Design-LDR 280_2.PPT