Bioequivalence and Bioavailability Forum

Post hoc power - power of which test? [General Sta­tis­tics]

posted by d_labes  – Berlin, Germany, 2014-03-14 14:53 (4134 d 10:40 ago) – Posting: # 12624
Views: 9,232

Dear Kumar Naidu,

❝ I have one study result with me of diuretic class drug. The study was refrence replicated study with N=50. The result obtained is given below

❝ Cmax - 91.41(83.04 - 100.62), CV=34.25, Power=96.82

❝ AUC(0 to t)- 90.14(85.78 - 94.72) , CV=17.31, Power=100.00

I'm not a friend of calculating post-hoc power . Search the forum to see why.

But if you nevertheless insist to do so, I think it should be the right power, namely the power of the BE test (90% confidence intervals contained in the acceptance range 80-125 or, alternatively, two one-sided t-tests TOST). And sorry, I couldn't reproduce your numbers in calculating that power!

Using PowerTOST (not considering the unbalancedness within sequence groups) I obtain:
#Cmax
power.TOST(CV=0.3425, theta0=0.9141, n=50, design="2x3x3")
#[1] 0.7421506
# AUC
power.TOST(CV=0.1731, theta0=0.9014, n=50, design="2x3x3")
# [1] 0.9902765

If your numbers are from Phoenix/WinNonlin see this thread to find out that the power values from that software are statistically nonsense.

Complete thread:

• Treat significance shri 2008-09-05 07:42 
  • Treat significance ElMaestro 2008-09-05 08:50
    • Denmark Ohlbe 2008-09-05 10:27
      • Denmark ElMaestro 2008-09-05 12:02
        • Denmark Ohlbe 2008-09-05 12:31
          • Denmark ElMaestro 2008-09-05 13:03
      • Denmark shri 2008-09-06 10:25
        • Statistically different or clinically different Ohlbe 2008-09-06 16:43
          • Statistically different or clinically different shri 2008-09-08 06:29
            • Statistically different or clinically different kumarnaidu 2014-03-14 06:54
              • Statistically different or clinically different ElMaestro 2014-03-14 07:10
                • Statistically different or clinically different kumarnaidu 2014-03-14 12:36
              • Post hoc power #666 Helmut 2014-03-14 13:31
              • Post hoc power - power of which test?d_labes 2014-03-14 13:53
                • Post hoc power - power of which test? kumarnaidu 2014-03-15 10:56