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Flashcards in t-tests Deck (5)
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Is it possible to totally avoid making a Type I error?

 Only if you test the entire population!
 There is always a chance of a Type I error when inferring a
significant effect from sample to population


What does a positive skew show?

Low scores over represented
 ‘Tail’ in the +ive direction


What does a negative skew show?

-High scores over represented
 ‘Tail’ in the –ive direction


Homogeneity of variance?

Want variance to be the same (or similar) in all groups
-Homogeneity = same
-Heterogeneity = different


Why no homogeneity of variance in repeated measures?

-Parametric assumption: Independence of observations
-One data point should not influence another
-BUT – repeated measures, so can’t avoid this!
-If my memory is bad it will be bad in both conditions
-In repeated designs random variance is reduced
-No individual differences between condition
-In repeated designs there is a different assumption - Sphericity: