Oops! df! [Study As­sess­ment]

posted by d_labes  – Berlin, Germany, 2019-02-21 10:54 (790 d 04:07 ago) – Posting: # 19956
Views: 7,125

Dear Helmut,

» » » Degrees of freedom?
» »
» » Presumable YES. ... Maybe they are or can be different, IIRC. Why ever.
» ANOVA: 30 (well…)
» TaaTP:
»   B/A 8
»   C/A 8
»   D/A 9
» 8? 9?? What the heck? ... I don’t get it.

Ok, something like that I have expected.
Let's try a 'theoretical' approach. Since we do not recode the periods and / or sequences the df can be obtained via (model without decomposition of the subjects effect into sequence and subject within sequence, design 4x4)

source    df
Total    2*n-1 = 23
treat    t-1   =  1
period   p-1   =  3
subject  n-1   = 11
error    n-4   = 23-1-3-11 = 8

So far so good. Two numbers of three 'explained'. Why the heck the comparison D/A has one degree of freedom more: Duno :confused:.
We have already noticed a similar effect for the EMA 'crippled' model for replicate designs. See this post.

Nevertheless: The degrees of freedom are different for the 2x2 design and the design of the TaaTP. We can mimic the df's, at least approximately, if we use the robust df's.



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