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martin
Senior

Austria,
2018-07-23 20:17

Posting: # 19086
Views: 720
 

 visualization of power-law model [General Sta­tis­tics]

Dear colleagues,

I would be happy to get the forum members thoughts regarding graphical display of the outcome of a dose-proportionality assessment based on the power-law model

In case that the power law model used to assess dose proportionality consists only of fixed factors intercept and slope I would think a figure like Figure 1 and 3 in the Smith et al paper (Smith et al. , 2000. Confidence interval criteria for assessment of dose proportionality. Pharm Res. 17:1278-1283) is good way to go.

However, frequently the corresponding model includes period and sequence effect as additional fixed effects (e.g. Williams design) and I am looking for some thoughts how to adequately visualize the corresponding results (other than showing the observed data and corresponding predictions grouped by sequence and period in a lattice plot or residual plots).

Best regards

Martin
d_labes
Hero

Berlin, Germany,
2018-07-26 14:49

@ martin
Posting: # 19105
Views: 589
 

 visualization of power-law model

Dear Martin,

» In case that the power law model used to assess dose proportionality consists only of fixed factors intercept and slope I would think a figure like Figure 1 and 3 in the Smith et al paper (Smith et al. , 2000. Confidence interval criteria for assessment of dose proportionality. Pharm Res. 17:1278-1283) is good way to go.

I think so.

» However, frequently the corresponding model includes period and sequence effect as additional fixed effects (e.g. Williams design) and I am looking for some thoughts how to adequately visualize the corresponding results (other than showing the observed data and corresponding predictions grouped by sequence and period in a lattice plot or residual plots).

For sake of simplicity I would go with the same plots as in the first case.
Only if period effects and/or sequence effects have a greater magnitude than the power law you will have a scatter in the data which seems not fit. I would expect such an behavior in only very rare cases, if any. If you have such a case, 'correct' your data for the period and/or sequence effects and plot then.

Hope you are well.

Regards,

Detlew
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