Fixed effects model: changing the F, p values [Two-Stage / GS Designs]

posted by zizou – Plzeň, Czech Republic, 2016-10-11 01:06  – Posting: # 16713
Views: 26,787

Dear mittyri,
for the results consistency (R versus Phoenix as you reported), there should be one more term of marvelous effect x) ... you posted it as number 7: (I resorted it for comparison of F and p values, note: int and Trt are missing in the results from R code)
»   Dependent Hypothesis Numer_DF Denom_DF        F_stat     P_value
» 5   Ln(Var)  Group*Per        2       14 3.2110481e+00 0.071153125
» 7   Ln(Var)  Trt*Group        1       14 2.3942317e-01 0.632200219
» 2   Ln(Var)      Group        1       14 9.9615453e-01 0.335181899
» 3   Ln(Var)        Seq        1       14 9.7094813e-01 0.341167964
» 4   Ln(Var)  Group*Seq        1       14 5.7364354e-02 0.814182229
» 1   Ln(Var)        int        1       14 3.1047428e+03 0.000000000
» 6   Ln(Var)        Trt        1       14 3.4404496e+00 0.084798088


If you change the muddle:
muddle <- lm(log(Var)~Group+Seq+Seq*Group+Subj%in%(Seq)+Per%in%Group+Trt+Group*Trt, data=data)
and run the mentioned code... Voilà!
Type III sum of squares:
(mimicing SAS/SPSS but with Seq tested against Subj)

log(Var) ~ Group + Seq + Seq * Group + Subj %in% (Seq * Group) + ...
               Df  Sum Sq   Mean Sq  F value     Pr(>F)   
Group:Per       2 0.04514 0.0225681  3.21105   0.071153 . 
Group:Trt       1 0.00168 0.0016827  0.23942   0.632200   
Group           1 0.22546 0.2254640  0.79946   0.386368   
Seq             1 0.27383 0.2738263  0.97095   0.341168   
Group:Seq       1 0.01618 0.0161779  0.05736   0.814182   
Group:Seq:Subj 14 3.94827 0.2820195 40.12641 7.5802e-09 ***
Residuals      14 0.09840 0.0070283                       
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

The comparison is telling us that with groups it will be little bit more complicated.

» Now Group factor seems to be more suitable.
» What bothers me is that Group effect is not equal in R and PHX, cannot figure out the reason
Good luck!
zizou

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