Bioequivalence and Bioavailability Forum

pristine, genuine, holy, magnificent, inexplicable beautiful variation [General Sta­tis­tics]

posted by ElMaestro  – Denmark, 2019-08-08 12:06 (1863 d 09:19 ago) – Posting: # 20486
Views: 8,653

Hi Hötzi,

❝ The precise model to be used for the analysis should be pre-specified in the protocol. The statistical analysis should take into account sources of variation that can be reasonably assumed to have an effect on the response variable.

❝ Is it reasonable to assume that groups or sequences have an effect on the PK response? Heck, no way! Same inclusion-/exclusion-criteria and hence, similar demographics, same clinical site, same bioanalytical method. Hundreds (thousands?) of studies performed in multiple groups and accepted by European agencies based on pooled data.

But on the other hand: Why then then include e.g. period?

Let us for a moment disregard the actual wording. I don't think this is about assuming that some factor has or hasn't an effect (and not about significance in the statistical sense either). As I see it I want to construct a CI which is as wide as my real uncertainty dictates. I start out with a whole bunch of ugly variation and in the fashion of Michelangelo working on his crude blocks of marble I chip parts and bits away from my bulk of variation by applying my model. What I have left of my variation is a chunk of pristine, genuine, holy, magnificent, beautiful variation. What a sight to behold , and whose origin my experimental setup cannot account for, which I therefore use for my CI. My confidence interval now is as wide as just exactly that uncertainty merits.

For a crossover this is of little practical importance since subjects are in groups. For a parallel trial I think I want group in the model. If regulators don't like this, they can ask me to take it away. I happily do so without protesting. I am a sheep at that point. But not until then.

Complete thread:

• Group by sequence interaction Mutasim 2019-08-07 13:16 [General Sta­tis­tics] 
  • Group by sequence interaction, an urban myth? Helmut 2019-08-07 14:35
    • pristine, genuine, holy, magnificent, inexplicable beautiful variationElMaestro 2019-08-08 10:06
      • I love your subject line! Helmut 2019-08-08 10:31
        • Group effect, did you miss it? Astea 2019-12-21 14:12
          • Group effect, did you miss it? PharmCat 2019-12-22 01:37
          • Group effect: the endless story Helmut 2019-12-22 10:30
            • Group effect: the endless river Astea 2019-12-22 21:23
              • Group effect: the endless river PharmCat 2019-12-22 22:52
              • replicateBE solution with interactions mittyri 2019-12-23 14:30
                • replicateBE solution with interactions Astea 2019-12-23 17:26
                  • datasets issues mittyri 2019-12-24 10:53
                  • datasets Helmut 2019-12-24 11:03
                    • datasets Astea 2019-12-24 19:18
                      • lmer / lme Helmut 2019-12-25 19:12
          • What do you mean exactly? Beholder 2019-12-27 13:44
            • What do you mean exactly? Astea 2019-12-29 21:59
              • ANOVA acc. to GL Helmut 2019-12-30 12:32