degrees of freedom [Power / Sample Size]

posted by d_labes  – Berlin, Germany, 2013-05-10 10:12 (4781 d 23:12 ago) – Posting: # 10564
Views: 8,982

Dear John,

❝ Question (obvious answer I am sure). The degrees of freedom for a 3-period 3-sequence 2-treatment partial replicate should be similar to that of a 3-period 3-sequence 3-treatment crossover right?


Define similar :-D.

If you need the exact ones:
Have a look at known.designs():
    no   design    df df2 steps  bk bknif       bkni                name   
     0 parallel   n-2 n-2     2 4.0   1/1 1.00000000         2 parallel groups
...
4    2      3x3 2*n-4 n-3     3 2.0   2/9 0.22222222             3x3 crossover
5    3    3x6x3 2*n-4 n-6     6 2.0  1/18 0.05555556           3x6x3 crossover
...
10   9    2x3x3 2*n-3 n-3     3 1.5   1/6 0.16666667 partial replicate (2x3x3)
...


df are the usual degrees of freedom if you use Proc GLM or equivalent.
df2 are the so-called robust degrees of freedom obtained if you analyze via appropriate intra-subject contrasts for T-R averaged over sequence groups.

Regards,

Detlew

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