Setup in Phoenix/WinNonlin [Study As­sess­ment]

posted by Helmut Homepage – Vienna, Austria, 2016-05-15 14:47  – Posting: # 16305
Views: 15,580

Hi Angus,

» My apologies it is a typo it is 95% not 98%.

Whew! Confused me. ;-)

» I am happy with the Phoenix WinNonlin calculations for within subject and between subject variance. The reason for my interest is the other worker following Smith's method is producing values, which are much lower than my Phoenix values for within subject variance. It seems to me that the values from the two methods should be much the same?

Variances should be similar. Smith’s data don’t help because the information is incomplete (cross-over or paired, sequences, periods?). Here one of my studies (6×3 Williams’ design):
                      dose-norm.       power-model       
                          BE       w = 1   w = 1/ln(dose)
Var(sequence*subject)  0.1593     0.1645      0.1595     
Var(Residual)          0.02284    0.02330     0.007113   


» I do see that LnCmax cannot be both the dependent and the regressor (I think LnDose is the regressor).

Exactly. I uploaded a project-file at Certara’s forum. Compare it to your setup.

» I have tried to run the linear mixed effects model, but I cannot repeat your results. The program ran, but my residual variance was 0.154. I am thinking that maybe my input file does not have the structure needed, e.g. subject 4,5,6 in the Smith Data were treated at 50mg and 250mg so do you need to differentiate by including a period 1 and period 2 variable in the input file?

I have no clue how the subjects were treated… Maybe it was a dose escalation?
      period  
    1   2   3 
1  25         
2  25         
4      50  250
5      50  250
6      50  250
7      75  250
8      75  250
9      75  250

Cheers,
Helmut Schütz
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