Bioequivalence and Bioavailability Forum

Geometric mean and CV [Power / Sample Size]

posted by Helmut  – Vienna, Austria, 2019-09-06 20:15 (2472 d 04:36 ago) – Posting: # 20549
Views: 12,107

Hi Rocco,

❝ So basically your analysis follows from the fact that the variance of the difference of T and R equal the sum of the variance of T and the variance of R, correct?

Well, you have four variance components (s²_wR, s²_wT, s²_bT, s²_bR). Then

1. Full replicate designs
   All are identifiable.
   
2. 2×2×2 crossover (balanced and complete for simplicity – otherwise, weighting is required)
   s²w = (s²_wR + s²_wT)/2 and s²_b = (s²_bT + s²_bR)/2.
   
3. 2 group parallel
   Only the pooled (total) s²_p. With a tricky mixed-effects model you could get s²_pT and s²_pR.
   
4. One treatment (FIM)
   Only s²_p.

Hence, if you want to plan #3 based on #4 you have to assume that the variances (within, between) of T and R are at least similar.

❝ And you are using the geometric CV as the estimate of CVp for R?

Yes.

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна! 
Helmut Schütz


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Complete thread:

• Input for CV when small first-in-man has been run Rocco_M 2019-09-03 18:45 
  • Geometric mean and CV Helmut 2019-09-05 14:05
    • Geometric mean and CV Rocco_M 2019-09-05 23:49
      • Geometric mean and CV Helmut 2019-09-06 00:15
        • Geometric mean and CV Rocco_M 2019-09-06 17:49
          • Geometric mean and CVHelmut 2019-09-06 18:15
            • Geometric mean and CV ElMaestro 2019-09-06 19:03
              • Geometric mean and CV Helmut 2019-09-07 09:57
                • Geometric mean and CV Rocco_M 2019-09-09 13:31
                  • Assumptions… Helmut 2019-09-09 14:09
                    • Assumptions… Rocco_M 2019-09-09 16:35
                      • Assumptions… Helmut 2019-09-09 17:19
                        • Assumptions… Rocco_M 2019-09-13 21:28
                          • t-test & Welch-test Helmut 2019-09-14 00:16
                            • sampleN.TOST and CI.BE Rocco_M 2019-09-17 22:02
                              • assumptions vs. realizations Helmut 2019-09-18 11:04