Sampling & External ValidityExternal Validity: CritiquingSlide 3Slide 4Slide 5Slide 6Sampling TerminologyKNR295SamplingSlide 1Sampling & External ValidityChapter 2KNR 295:SamplingSlide 2External Validity: CritiquingThe sampling model…KNR 295:SamplingSlide 3External Validity: CritiquingThe sampling model…Goal (claim) is representative samplingOften not attainable - Who to generalize to?Availability of the true “representative” sample?Will the sample be representative of other times?An alternative is to model (or critique) the differences in a systematic way…KNR 295:SamplingSlide 4External Validity: CritiquingProximal similarity model (Campbell, 1963)KNR 295:SamplingSlide 5External Validity: CritiquingProximal similarity model (Campbell, 1963)The idea here is to quantify the difference between the various properties of the study you are considering, and that to which you want to generalize, and then consider the likelihood that this difference would alter the research’s findingsKNR 295:SamplingSlide 6External Validity: CritiquingWhat to do?Evaluate, critique, consider…And if that fails, replicateKNR 295:SamplingSlide 7Sampling