Establishing a Cause-Effect RelationshipInternal ValidityEstablishing Cause and EffectSlide 4Slide 5Slide 6Slide 7Establishing Cause and EffectSlide 9In Lab or Field Experiments…Single-Group Threats to Internal ValidityThe Single Group CaseSlide 13Slide 14Slide 15ExampleExample: What Kind of Design?History ThreatMaturation ThreatRuling Out a Maturation ThreatTesting ThreatInstrumentation ThreatMortality ThreatRegression ThreatMultiple-Group Threats to Internal ValidityThe Central IssueThe Multiple Group CaseSlide 28Selection ThreatsSelection-History ThreatSelection-Maturation ThreatSelection-Testing ThreatSelection-Instrumentation ThreatSelection-Mortality ThreatSelection-Regression Threat“Social Interaction” Threats to Internal ValidityWhat Are “Social” Threats?Types of DesignsSlide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Design Notation ExampleElements of a DesignSlide 50Slide 51Slide 52Slide 53Slide 54Slide 55Design ExampleSlide 57Slide 58Slide 59Slide 60Slide 61Establishing a Cause-Effect Establishing a Cause-Effect RelationshipRelationshipEstablishing a Cause-Effect Establishing a Cause-Effect RelationshipRelationshipInternal ValidityInternal ValidityInternal ValidityInternal Validity•The “treatment” and the “outcomes”The “treatment” and the “outcomes”•The independent and dependent variables.The independent and dependent variables.ObservationObservationObservationObservationTreatmentTreatmentOutcomesOutcomesWhat you What you dodoWhat you What you seeseeIs the relationship Is the relationship causalcausal between... between...AlternativeAlternativecausecauseAlternativeAlternativecausecauseAlternativeAlternativecausecauseAlternativeAlternativecausecauseIn In thisthis study studyEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectTemporal precedenceTemporal precedenceTemporal precedenceTemporal precedenceEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectTemporal precedenceTemporal precedenceTemporal precedenceTemporal precedenceCauseCauseEffectEffectthenthenTimeTimeIt can get complicated through:It can get complicated through:-sloppiness (campaign contributions-sloppiness (campaign contributions- Chicken and egg cyclical functions - Chicken and egg cyclical functions (democracy and GDP)(democracy and GDP)Establishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectTemporal precedenceTemporal precedenceTemporal precedenceTemporal precedenceCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectCauseCauseEffectEffectthenthenTimeTimeEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectTemporal precedenceTemporal precedenceTemporal precedenceTemporal precedenceCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectCauseCauseEffectEffectthenthenTimeTimeif X, then Yif X, then Yif if notnot X, then X, then notnot Y Yif treatment given, then outcome observed (usually)if treatment given, then outcome observed (usually)if program if program notnot given, then outcome given, then outcome notnot observed observedEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectTemporal precedenceTemporal precedenceTemporal precedenceTemporal precedenceCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectCauseCauseEffectEffectthenthenTimeTimeif X, then Yif X, then Yif if notnot X, then X, then notnot Y Yif program given, then outcome observedif program given, then outcome observedif program if program notnot given, then outcome given, then outcome notnot observed observedDosage effects or comparative statics:Dosage effects or comparative statics:If If moremore of treatment, then of treatment, then moremore of outcome observed of outcome observedif if lessless of treatment given, then of treatment given, then lessless of outcome observed of outcome observedEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectTemporal precedenceTemporal precedenceTemporal precedenceTemporal precedenceCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectNo alternative No alternative explanationsexplanationsNo alternative No alternative explanationsexplanationsCauseCauseEffectEffectthenthenTimeTimeif X, then Yif X, then Yif if notnot X, then X, then notnot Y YTreatmentTreatmentOutcomeOutcomeMicromediationMicromediationEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectEstablishing Cause and EffectTemporal precedenceTemporal precedenceTemporal precedenceTemporal precedenceCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectCovariation of cause and effectNo alternative No alternative explanationsexplanationsNo alternative No alternative explanationsexplanationsCauseCauseEffectEffectthenthenTimeTimeif X, then Yif X, then Yif if notnot X, then X, then notnot Y YTreatmentTreatmentOutcomeOutcomeMicromediationMicromediationAlternativeAlternativecausecauseAlternative causeAlternative cause(nuisance) (nuisance) AlternativeAlternativecausecauseAlternative causeAlternative cause(substantive)(substantive)In Lab or Field Experiments…In Lab or Field Experiments…In Lab or Field Experiments…In Lab or Field Experiments…Is taken care of because you Is taken care of because you intervene before you measure intervene before you measure outcomeoutcomeIs measured by comparing Is measured by comparing treated and untreated groupstreated and untreated groupsIs the central issue of internal Is the central issue of internal validity -- usually taken care of validity -- usually taken care of through random assignmentthrough random assignmentTemporal Temporal precedenceprecedenceCovariation of Covariation of cause and effectcause and effectNo alternative No alternative explanationsexplanationsSingle-Group Threats to Internal Single-Group Threats to Internal ValidityValiditySingle-Group Threats to Internal Single-Group Threats to Internal