Model Type III Sum of Squares [General Sta­tis­tics]

posted by Obinoscopy  – USA, 2018-12-16 08:58 (1812 d 06:50 ago) – Posting: # 19695
Views: 6,473

(edited by Obinoscopy on 2018-12-16 10:42)

Hi Guys,

I have been looking at the SAS outputs of several Bioequivalence Studies.

The statistical analysis of the several BE experiment was done using PROC GLM effect ANOVA model with main effect of treatment, period, sequence and subjects nested within sequence as fixed effects.

Most of them are Balanced 2x2x2 BE designs.

Now the issue is that I noticed that the Type III Sum of Squares of the Model is not always equal to the sum of the individual Sum of Squares of the various main effects (treatment, period, sequence and subject nested with sequence) for the SAS Outputs I've looked at.

I've checked this several times and keep finding out that I don't get the Model SS if I add the various SS of the main effects. But the df for the Model is always equal to the sum of the dfs of the main effects. My rudimentary knowledge of ANOVA is that they are supposed to be the same (both sum of SSs and dfs) . What could be the cause of the discrepancy in sum of SSs? Is it because we assumed in this model that there are no interactions?



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