Lessons learned? [Regulatives / Guidelines]

posted by ElMaestro  – Denmark, 2011-08-28 23:34 (4622 d 23:48 ago) – Posting: # 7307
Views: 6,327

Hi all,

quick note:
There is a sequence effect to be fit, no doubt about that.

The fact that we boil TRTR and RTRT down to RR is not the direct culprit here as treatment is not considered. But as was said by Helmut there is an interaction or nesting of period in sequence. So just as is the case with subejcts, whenever period is in the Muddle, any type III anova goes bonkers.
Compare the two sequential ones:

Muddle=lm(log(b$Data)~factor(b$Period) + factor(b$Sequence))
anova(Muddle)
Analysis of Variance Table

Response: log(b$Data)
                  Df Sum Sq Mean Sq F value Pr(>F)
factor(b$Period)   3   1.57 0.52326  0.5752 0.6322
Residuals        146 132.81 0.90968

Muddle=lm(log(b$Data)~factor(b$Sequence) + factor(b$Period))
anova(Muddle)
Analysis of Variance Table

Response: log(b$Data)
                    Df  Sum Sq Mean Sq F value Pr(>F)
factor(b$Sequence)   1   0.088 0.08801  0.0968 0.7562
factor(b$Period)     2   1.482 0.74088  0.8144 0.4449
Residuals          146 132.813 0.90968 



Remember earlier discussions about three-treatment designs where EMA occasionally does not like that the residual is polluted by an irrelevant treatment A when comparison of treatment B and C is done. In those cases the dataset is pruned down to a "pseudo" two-treatment, two-sequence, two-period dataset and analysed the usual way. We could do the same to periods here and get rid of the ugly 'issue', I think. I don't think this will change the residual SS (which is what is important), however, but I haven't done it or thought it fully through.

Pass or fail!
ElMaestro

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