Causal-ComparativeCausal-ComparativeResearchResearch

July 23, 2001July 23, 2001EAF 410EAF 410

What is it?What is it?• AssociationalAssociational• Differences between/among groupsDifferences between/among groups

– Categorical dataCategorical data– Differences already existDifferences already exist

• Ex post factoEx post facto• Much research in medicine & Much research in medicine &

sociologysociology

ExamplesExamples• What are the effects What are the effects

of teacher gender on of teacher gender on student behaviorstudent behavior

• How are How are administrative administrative decisions affected decisions affected by genderby gender

• What causes What causes students to join the students to join the glee club?glee club?

• How are teaching How are teaching styles affected by styles affected by graduate studies?graduate studies?

Type 1Type 1• Exploration of Exploration of effects effects caused by caused by

membership in a groupmembership in a group– What differences in student behavior What differences in student behavior

are caused by gender?are caused by gender?

Type 2Type 2• Studies Studies causescauses of group of group

membershipmembership– Why do ISU students enroll in EAF Why do ISU students enroll in EAF

410 during the summer session?410 during the summer session?

Type 3Type 3• Studies the Studies the consequencesconsequences of an of an

interventionintervention– How do students who have taken How do students who have taken

EAF 410 evaluate research articles?EAF 410 evaluate research articles?

Causal Link TentativeCausal Link Tentative• Does Does gendergender cause differences? cause differences?

– Girls read betterGirls read better– Boys are disciplined moreBoys are disciplined more

• Other probable links in the causal Other probable links in the causal chainchain

Basic ApproachBasic Approach• Noted difference between two Noted difference between two

groupsgroups• Look for causes/consequencesLook for causes/consequences

Similarities with Similarities with Correlational ResearchCorrelational Research

• AssociationalAssociational• Attempt to explain phenomenaAttempt to explain phenomena• Often lead to experimental researchOften lead to experimental research• Don’t allow variable manipulationDon’t allow variable manipulation• Attempt to explore causationAttempt to explore causation

Causal-ComparativeCausal-Comparative-compare groups-compare groups-categorical variable(s)-categorical variable(s)-crossbreak tables-crossbreak tables

CorrelationalCorrelational-individual scores-individual scores-quantitative variables-quantitative variables-scatterplots & -scatterplots & rr

Similarities with Similarities with Correlational ResearchCorrelational Research

Steps InvolvedSteps Involved• Identify & clarify research problemIdentify & clarify research problem

– Several alternative hypothesesSeveral alternative hypotheses• Select subjects (groups)Select subjects (groups)

– Homogenous on some variablesHomogenous on some variables• InstrumentationInstrumentation

– No limitsNo limits

Steps InvolvedSteps Involved(continued)(continued)

• DesignDesign– Groups differ on specific variableGroups differ on specific variable– Groups compared on other variable(s)Groups compared on other variable(s)

Evaluating ThreatsEvaluating Threats• What other factors affect the What other factors affect the

comparison variable?comparison variable?• What is the likelihood of the What is the likelihood of the

groups differing on these factors?groups differing on these factors?• Evaluate threats on likelihood of Evaluate threats on likelihood of

their effect and plan to control.their effect and plan to control.

Survey ResearchSurvey ResearchJuly 23, 2001July 23, 2001

EAF 410EAF 410

Three CharacteristicsThree Characteristics• Information collected to describeInformation collected to describe• Information collected by asking Information collected by asking

questionsquestions• Information collected from a Information collected from a

samplesample

Major PurposeMajor Purpose• To describe the characteristics of a To describe the characteristics of a

populationpopulation• Not so concerned about Not so concerned about whywhy• Concerned about Concerned about what iswhat is

Types of SurveysTypes of Surveys• Cross-sectional StudyCross-sectional Study

– information collected at just one information collected at just one point in timepoint in time

• Longitudinal StudyLongitudinal Study– information collected at different information collected at different

points in timepoints in time

Types of Longitudinal Types of Longitudinal StudiesStudies

• TrendTrend– Different samplesDifferent samples– Population may changePopulation may change

• CohortCohort– Different samplesDifferent samples– Population doesn’t changePopulation doesn’t change

Types of Longitudinal Types of Longitudinal StudiesStudies (continued)(continued)

• PanelPanel– Same sampleSame sample– Population doesn’t changePopulation doesn’t change

Steps in Survey ResearchSteps in Survey Research• Clearly define objectivesClearly define objectives• Construct clear questionsConstruct clear questions• Sample (unit of analysis)Sample (unit of analysis)• Collect dataCollect data

– ““live” to a grouplive” to a group– mailmail– phonephone– face-to-face interviewsface-to-face interviews

Preparing the InstrumentPreparing the Instrument• Not too longNot too long• Questions easy to answerQuestions easy to answer• Carefully wordedCarefully worded

– can be asked as writtencan be asked as written– will mean same to allwill mean same to all– can be answeredcan be answered– will be answeredwill be answered

Types of QuestionsTypes of Questions• Closed-endedClosed-ended

– answers providedanswers provided• Open-endedOpen-ended

– respondent provides answersrespondent provides answers

Suggestions for Closed-Suggestions for Closed-Ended QuestionsEnded Questions

• UnambiguousUnambiguous• Simple focusSimple focus• ShortShort• Common languageCommon language• ““Unbiased” termsUnbiased” terms• Not leading questionsNot leading questions• No double negativesNo double negatives

Suggestions for QuestionsSuggestions for Questions• Try them out on a similar sampleTry them out on a similar sample• Make them look goodMake them look good• Have follow-up questionsHave follow-up questions

– contingency questions -- contingent contingency questions -- contingent on answer to previous questionon answer to previous question

NonresponseNonresponse• Some will not return surveySome will not return survey• Some items will not be answeredSome items will not be answered• Can use random replacementCan use random replacement