## The mysterious ρ -between or within studies [General Sta­tis­tics]

Dear Helmut! Dear all!

❝ Current state of affairs about the mysterious ρ

That's not the whole truth about the state of affairs .
The question is: Correlation of treatment differences between studies or within studies.

For the latter I recall you two references:
Phillips KF.
Power for Testing Multiple Instances of the Two One-Sided Tests Procedure
Int J Biostat. 2009;5(1):Article 15. doi:10.2202/1557-4679.1169

Hua SY, Xu S, D’Agostino RB Sr.
Multiplicity adjustments in testing for bioequivalence
Stat Med. 2015;34(2):215–31. doi:10.1002/sim.6247

Quote from Kem Phillips:
"The correlation will usually be difficult to estimate, unless a similar experiment has been conducted...".
That smells for me like within a study.

Definition in Hua et al., Section 2, clearly is within a study. Although Ben doubt the correctness of the formulas for ρ given in that paper. Note further that the observed alpha-inflation in that paper is crap. The IUT principle protects us from the need to adjust alpha.

Regards,

Detlew