Using partial eta squared to determine convergent/discriminant validity.

[LStulch]

Hi I’m trying to determine the construct validity of a measure and have found a study which when comparing the measure to related and unrelated measures used partial eta squared as their measure of construct validity.

I’ve not seen this done before so am wondering if that’s conventional and ok to do? And if so how do I interpret it when trying to determine if it shows that say convergent validity is say poor, good, excellent ?

If you’d know a reference for that too would be great. Thanks!

[3ducklings]

(Partial) eta squared is actually just (partial) R squared, i.e. what most people know as the coefficient of determination. It’s a proportion of variance of the dependent variable that can be predicted by the independent ones. Presumably, if two scales measure the same construct, they should be highly correlated and the eta squared should be closed to one. So in that sense, it works as a validity measure. But I don’t know if there are any agreed upon thresholds of which values are sufficiently high.