Bioequivalence and Bioavailability Forum • Comprehension problem

Comprehension problem [Power / Sample Size]

posted by Helmut – Vienna, Austria, 2013-03-10 00:34 (4858 d 00:53 ago) – Posting: # 10178
Views: 6,030

Dear all & esp. Detlew! :-D

I know that Balaam’s design (RT|TR|RR|TT) is not very powerful since only ½ of the sequences are “used” in the T-R comparison (the other half is luxury – giving s²_WR and s²_WT). What puzzles me is

require(PowerTOST)

sampleN.TOST(CV=0.3, design="2x4x2", print=F)

  Design alpha  CV theta0 theta1 theta2 Sample size Achieved power Target power

1  2x4x2  0.05 0.3   0.95    0.8   1.25         152      0.8067485          0.8

compared to

sampleN.TOST(CV=0.3, design="2x2", print=F)

  Design alpha  CV theta0 theta1 theta2 Sample size Achieved power Target power

1    2x2  0.05 0.3   0.95    0.8   1.25          40      0.8158453          0.8

152/2=76 subjects in Balaam’s design resemble TR|TR which is obviously ≫ than the 40 needed in a conventional 2×2. :confused:

If I politely ask

power.TOST(CV=0.3, design="2x2", n=76)

[1] 0.9732043

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Complete thread:

Comprehension problemHelmut 2013-03-09 23:34 [Power / Sample Size]
- Baalam's design N d_labes 2013-03-11 15:46
  - Baalam's design N Helmut 2013-03-11 16:18