how to think scientifically methods of conducting research...
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} Howtothinkscientifically} Methodsofconductingresearch} Ethicalconcernsinresearch
ResearchMethodsinPsychology
} Scienceisaprocessofobservation.} Notallobservationsarescientific.
– Question:Howdoessciencedifferfromeverydayobservation
• Considerthebeliefthat“oppositesattract”?
ThinkingLikeaScientist
} First,sciencereliesonobjectivityratherthansubjectivity.– Scientistsstrivetobeobjective
• Anyobservationbyahumanbeingisbydefinition,subjective.
– Recognizingwhenyouarebeingsubjectivecanbedifficult
• Demandevidence!Anecdoteisthebaneoflogic!
– Scientistscannotrelyontheirownintrospectionstomaintainobjectivity.
• Scientificmethodspromoteobjectivityandhelppreventbiased,subjectiveobservationsfromdistortingascientist’swork.
ThinkingLikeaScientist
} Second,sciencereliesonsystematicobservationasopposedtohit-or-missobservation.– By“hitormiss,”wemeanmakingconclusionsbasedonlyonwhateverishappeningaroundus.
• E.g.,N=1“singlecase”observations.
ThinkingLikeaScientist
} Finally,sciencereliesonobservable,repeatable evidence.– Everydayobservationoftenignorescontradictoryevidence,especiallywhenitrunscountertostronglyheldbeliefs.
– “Oneoff”observationsarelesstellingthanconsistentpatternsofbehavior.
ThinkingLikeaScientist
} Scienceseekstodevelopgoodtheories– Setsoffactsandrelationshipsbetween factsthatcanbeusedtoexplainandpredictphenomena.
} Allresearchmustbeginwiththeory.} Research isatheorybuildingandtestingendeavor.
} Theorybuildingandtestingentailsgeneratinghypothesesthatarethensystematicallyexamined(i.e.,tested).
} Hypotheses thatarenotrejectedcontributetothetheoryandhelpgeneratenewhypotheses.
TheoryTesting&TheResearchProcess
} Scientifichypothesesmustbebothfalsifiableandtestable.– Falsifiabledoesnotmean“false.”– Falsifiablemeansthatyoucanimaginesituationsthatdemonstrateyourhypothesistobefalse.
• IfIhypothesize thatalllemonsaresour,tastingonethatisrelatively sweetwillfalsifythehypothesis.
• “Invisiblegorillahypothesis.”– Hypothesescanbefalsifiablebutnotnecessarilytestable
• Testablemeansyoucanevaluatethehypothesisusingknownscientificmethodsandobservationsofevents/behaviors thatactually occur.
– E.g.,voodooisanon-testableexplanationforbehavior.
TheoryTesting&TheResearchProcess
TheScientificMethod
• Remember:Themaingoalofpsychologicalresearchistotestideasaboutbehaviorviatheapplicationofthescientificmethod.– Asetofrulesforgatheringandanalyzinginformationthatenablesyoutotestanideaorhypothesis.
• Decisionsmadeateachstepofthescientificmethodwillultimatelyaffectthetypesofconclusionsdrawn.
TheScientificMethod(AsAppliedtoPsychologicalResearch)
Observebehaviororotherphenomena
Formulatearesearchquestion
Generateatestableprediction(hypothesis)thataddressesyourquestion
Collectandanalyzedata
Drawconclusionsandusethemtocreate/refinetheories
} Animportantpartofdecidingwhatyouaregoingtoresearchisdecidingthegroupyouwillbestudying.– “PerfectWorld”-- Researcherswouldincludeeverypersontheyareinterested instudying.
} Itisimpossibletotesteveryone,sowe“sample”asubsetofthepopulationofinterest– Thissampleshouldreflectthewholepopulationasmuchaspossible(i.e.,bearepresentativesample)
} Randomsamplingofparticipantsensuresarepresentativesample.– Morerepresentative=moregeneralizable– Randomsamplingisnotalwayspossible!
• Psychologicalresearchoftenusessamplesofconvenience,orgroupsofpeoplewhoareeasilyaccessibletotheresearcher.
SelectingParticipantsforaResearchStudy
} Surveysallowyoutoasklargenumbersofpeoplequestionsaboutattitudesandbehavior.– Quick&Cheap– MultipleModes(telephone,internet,paper-and-pencilforms)
} Samplingissues.– GoodNews:Accesslargesamplesthataretypical,orrepresentative,ofthepopulationyouwishtodescribe.
} Surveysuseself-report.– BadNews:Resultscanbeinfluencedbypeople’snaturaltendencytowanttoappearsociallyappropriate!
• Self-reportedbehaviorisn’tallthatreliable.
NonexperimentalMethods:Surveys
•Surveymethodsareoftenusedincorrelationalresearch.•Correlationalresearchmeasurethedirectionandstrengthoftherelationshipbetweentwovariables.
• E.g.,Height&Weight
•Process:•Obtainmeasuresofeachvariable.•Comparethevaluesofonevariabletothoseoftheotherandconductastatisticalanalysisoftheresultsusingacorrelationcoefficient.
DesigningaCorrelationalStudy
DesigningaCorrelationalStudy
} Thecorrelationcoefficient
MeasuringtheCorrelation
} Thethirdvariableproblem:– Thirdvariablescanberesponsibleforthecorrelationweobserveintwoothervariables.
– Correlationspermitustodiscusstherelationshipsbetweentwovariablesbuttellusnothingaboutwhetheronevariablecauseschangesintheother.
UnderstandingCausation
} Manipulateonevariableandobservechangesinothers– Independentvariable:themanipulated cause– Dependentvariable:themeasured effect
DesigninganExperimentalStudy
} Wewanttoensurethatourdependentvariablesreflecttheoutcomesofourindependentvariables,insteadofindividualdifferencesamongparticipants– E.g.,differencesinpersonalities,abilities,motivations,andothersimilarfactors.
} Topreventtheseindividualdifferencesfrommaskingeffectsofourindependentvariable,werandomlyassignparticipantstoexperimentalorcontrolgroups.
• Randomassignmentmeansthateachparticipanthasanequalchanceofbeingassignedtoanygroupinanexperiment.
AssigningParticipantGroupsinaStudy
} Withrandomassignment,differencesinthebehaviorofonegroupversusanotherareunlikelytheresultoftheindividualdifferencesamongtheparticipants,– Suchdifferencestendto“cancel”eachotherout!
• i.e.,becausepeoplehaveanequally-likely chanceofbeinginanygivenexperimentalcondition.
AssigningParticipantGroupsinaStudy
} Inexperimentalresearch,individualdifferencesmayactasconfoundingvariables– Variablesthatareirrelevanttothehypothesisbeingtestedthatcanalterourconclusions.
• Randomassignmenttogroupstypicallycontrolsforindividualdifferenceconfounds,butothersourcesexist.
• E.g.,Situationalconfounds,suchastimeofdayornoiselevelsinalaboratory,canalsoserveasconfounds.
ConfoundingVariables
} Otherconfounding(extraneous)variables– Experimenterbias
• Theunintentionaleffectthatresearchersmayexertontheirresults.
• Double-blinddesign
ProblemsinExperimentalResearch
Anexampleexperiment:DoesListeningtoMusicWhileStudyingAffectLearning?
ConductingEthicalResearch
AmericanPsychological Association GuidelinesDonoharm.Accuratelydescriberiskstopotentialparticipants.Ensurethatparticipationisvoluntary.Minimizediscomfort toparticipants.Maintainconfidentiality.Donotunnecessarilyinvadeprivacy.Usedeceptiononlywhenabsolutelynecessary.Providedebriefingtoallparticipants.Provideresultsandinterpretationstoparticipants.Treatparticipantswithdignityandrespect.Allowparticipants towithdrawatanytimeforanyreason.
} Thissectioncovers:– Issuesinmeasurement– Descriptivestatistics– Inferentialstatistics
} “Ifyoucan’tmeasureit,it’snotPsychology”
BehavioralStatistics
} Howdopsychologistsdrawconclusionsfromdata?
} Somepsychologistsspecializeinadministering,scoring,andinterpretingpsychologicaltests.– E.g,testsofintelligence,creativity,personality,oraptitude.
– Thisspecialty,whichiscalledpsychometrics,isanexampleofusingpsychologytopredictfuturebehavior.
– QuantitativePsychologyisasubfieldthatfocusesonrefiningstatisticalandmethodologicalproceduresusedinpsychologicalresearch.
BehavioralStatistics
} Measurement:Quantificationofpsychologicalvariables(i.e.,psychological“constructs”).– Reliability:consistency– Validity:accuracy
IssuesinMeasurement
} Findmeaningfulpatternsandsummariesinlargesetsofdata– MeasuresofCentralTendency
DescriptiveStatistics
TheMean
} A numeric average of a data set.§ Can be skewed by extreme values.
TheMedian
} The halfway mark in a set of data, with half of the scores above and half below
} Themostfrequentlyoccurringscore(s)inasetofdata
TheMode
} Measureshowtightlyclusteredagroupofscoresisaroundthemean
StandardDeviation
} Descriptivestatisticsareimportantforunderstandingthenatureourourdata(e.g.,distribution,averagelevels).
} Inferentialstatisticsallowustodecidewhethertheobserveddifferencesare“real”orjustduetochance.
} Howdoweknowwhenahypothesisshouldberejected?– Likemostsciences,psychologyhasacceptedoddsof5outof100thatanobservedresultisduetochanceasanacceptablestandardforstatisticalsignificance.
• Wecanassessthelikelihood ofobservingaresultduetochancebyrepeatingastudy,like throwingdicemultipletimes.
InferentialStatistics
} Conductingameta-analysis,orastatisticalanalysisofmanypreviousexperimentsonthesametopic,oftenprovidesaclearerpicturethansingleexperimentsobservedinisolation.– AndersonandBushman(2001)combinedthefindingsofover300studiesrepresentingmorethan50,000participants
– Apositiverelationshipexistsbetweenexposuretovideogameviolenceandaggression,aggressivecognitions,aggressiveaffectormood,andarousal.
MetaAnalysis
} Astatisticalanalysisofmanypriorexperiments
Example:AMeta-AnalysisofVideoGameViolenceandAggression
• This type of graph is known as a boxplot. • The width of each box
corresponds to the number of studies of each type.
• Twenty-five percent of the results fall below the bottom of the box and another 25% are above the top of each box.
• The line in the middle of a box shows the median, the point where half of the data are above and half below.