Bioequivalence and Bioavailability Forum

3-per, 2-trt designs and estimation of intra-subj. variance [RSABE / ABEL]

posted by ElMaestro  – Denmark, 2013-08-12 21:54 (4702 d 12:41 ago) – Posting: # 11264
Views: 14,433

Hi all,


I think it sounds fully plausible and intuitive to say that intrasubject variabilities for Test products cannot be estimated in TRR/RTR/RRT xover designs. We do not have replication of Test and this is the principal argument.

But is that really a reflection of the facts?

Well, due to the replication of Ref we can estimate s2wR as well as s2b, with w being 'within' and b being 'between'. I think it can be argued that in a crossover it makes no sense to discuss different betweens-variances between treatments.
Now, the variance of the observations done on test will be s2wT + s2b - this is what we will have on the diagonal of the covariance matrix V.
So, we can definitely estimate the sum (s2wT + s2b), and since the ref. replication allows us to get s2b, I see no reason why we cannot estimate the elusive s2wT.

Try to think about it without just blindly referencing what a guideline says.
Now butcher me, please.

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Edit: Category changed. [Helmut]

Complete thread:

• 3-per, 2-trt designs and estimation of intra-subj. varianceElMaestro 2013-08-12 19:54 [RSABE / ABEL] 
  • 3-per, 2-trt designs and estimation of intra-subj. variance Dr_Dan 2013-08-13 10:11
    • 3-per, 2-trt designs and estimation of intra-subj. variance ElMaestro 2013-08-13 15:00
      • TRT|RTR rulez! Helmut 2013-08-13 18:23
        • TRT|RTR rulez? Really? d_labes 2013-08-14 08:16
          • TRT|RTR rulez? Really? Yes. ElMaestro 2013-08-14 11:29
            • TRT|RTR rulez? Really? No. d_labes 2013-08-14 13:34
              • TRT|RTR rulez? Really? No. ElMaestro 2013-08-14 14:25
                • TRT|RTR Lost in formulas. d_labes 2013-08-14 16:35
          • TRT|RTR rulez? References Helmut 2013-08-14 13:44
            • References László & László d_labes 2013-08-14 19:12
              • Heteroscedasticity Helmut 2013-08-17 17:33
                • Heteroscedasticity: TRT|RTR rulez! d_labes 2013-08-29 16:45
                  • Heteroscedasticity: TRT|RTR rulez! ElMaestro 2013-08-29 17:50
                    • Sims & evaluation d_labes 2013-08-30 09:16
                      • Sims & evaluation ElMaestro 2013-08-31 14:11
                        • Evaluation subtleties d_labes 2013-08-31 17:20