When Small Effects are Impressive Deborah Prentice & Dale Miller

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Don’t mess with the bunny VS Big Impressive effect size bunny It may look like a small potato BUT It’s actually quite impressive… Small Potato effect It resembles a duck!

Outline Question: How do we know when a result is important? Answers: 1.Size Matters - Standard Practice: measure statistical strength 2.Some things other than size matter - Method matters

Size Matters Statistics quantify the size of an effect Standardized measures are useful Values are meaningful Results can be compared across studies But more importantly: We can quantify how Large and dreamily important the effect is! Large effects are impressive! But size is not the only thing that matters!

Size doesn’t matter Small effect can be really impressive –If no effect is expected, a small effect is a huge deal Method matters Alternative ways to demonstrate “impressiveness” –Minimal manipulation of independent variable –Difficult to influence dependent variable

Minimal Manipulation What makes this design impressive: –The manipulation of the IV is so slight that it shouldn’t account for any dependent variable variance … but it DOES Studies low on manipulation, high on interesting-ness, low on effect size: –Minimal group experiment –Mere exposure effect –Cookie = happy helper

Difficult to influence DV How does this design make a small effect impressive? –The dependant variable should be resistant to experimental manipulations …But it’s NOT Examples: –Judicial decisions and attractiveness –Conformity to group pressure

Summary 1.Statistics can quantify effect size 2.Important-ness of effect not equivalent to large-ness of effect 3.Small effects can be super impressive 4.Small effects are impressive when the IV shouldn’t affect the DV, but it does

Conclusions Small potato wins sometimes

Conclusions Small potato wins sometimes

Thank you!

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