Williams’ designs more reliable? [Design Issues]

posted by d_labes  – Berlin, Germany, 2012-11-08 09:29 (4158 d 16:09 ago) – Posting: # 9524
Views: 4,570

Dear Ben!

❝ ... But due to the design isn't it the case that a Williams design will give more reliable results in any case - even without adjusting for carry over in the model?


Why should it? :confused:
Same number of subjects, same number of degrees of freedom, same design constant. At least if we talk about the usual evaluation. So what mysterious feature should let to more reliable results?

In case we talk about the 'robust' evaluation (aka Senn's basic estimator) we have to analyse the T-R contrasts (in the log domain) via an ANOVA with sequence as effect in the model. The degrees of freedom to use are then N-nseq, where N=number of subjects, nseq=number of sequences.
That gives us:
          Latin square  Williams
3-period    N-3           N-6
4-period    N-4           N-4

A slight advantage of the Latin square in case of a 3-treatment-3-period study. Else also identical design features.

Regards,

Detlew

Complete thread:

UA Flag
Activity
 Admin contact
22,957 posts in 4,819 threads, 1,636 registered users;
76 visitors (0 registered, 76 guests [including 10 identified bots]).
Forum time: 01:38 CET (Europe/Vienna)

With four parameters I can fit an elephant,
and with five I can make him wiggle his trunk.    John von Neumann

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz
HTML5