Bioequivalence and Bioavailability Forum • Al Gore Rhythms

Al Gore Rhythms [🇷 for BE/BA]

posted by Helmut – Vienna, Austria, 2009-09-29 16:52 (5316 d 08:10 ago) – Posting: # 4269
Views: 39,276

Dear D Labes!

❝ Hope you have already waited for me.

Yesss!

❝ Here are the results of the SAS Proc Power.

❝ Seems the power is calculated in this case totally wrong!

Fascinating.

❝ My own rolled code (relying on Owens Q-functions, undocumented but available in SAS) gives:

That’s the more interesting part (homebrew)!

                        n  % power    n  % power

------------------------------------------------

#1 Diletti et al.       4 >70         6 >90

#2 PASS                 4  72.90

#3 D Labes' SAS code    4  72.9014    6  98.6992

#4 nQuery Advisor 7     4  71.559     6  97.943

#5 R-code               4  66.674     6  98.697

#6 FARTSSIE 1.6         4  66.674     6  98.697

#7 StudySize 2.0.1      4  15.9 (!)   6  93.201

n=4 takes the lead by 4:3! Observations:
#5 (based on Algorithm AS 243) and #6 give identical results. This is not surprising, because the VBA-routine within FARTSSIE was written by Russell V. Lenth, the author of AS 243. #2/3 agree; for n=6 power is comparable with #5/6. #4 calculates lower power than #1-3, but still would suggest n=4. The difference between #1-3 and #5/6 might be due to different algorithms for estimating the noncentral t-distribution (#1/3: ?, #2: AS 243?, #4: AS 184, #5/6: AS 243). #7 uses approximations (Ref. 2 in this post); however, yields conservative results.

Maybe I should contact Dieter Hauschke to join the party…

Edit: Many, many years later.

library(PowerTOST) res <- data.frame(method = c("exact", "mvt", "nct", "central"), n = NA_integer_, power = NA_real_) for (j in 1:nrow(res)) { res[j, 2:3] <- sampleN.TOST(CV = 0.075, theta0 = 1, targetpower = 0.7, method = res$method[j], print = FALSE)[7:8] } print(res, row.names = FALSE) method n power exact 4 0.7290143 mvt 4 0.7290142 nct 6 0.9869738 central 6 0.9611687

—
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Helmut Schütz

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Complete thread:

R-Code for Power in 2×2 Cross-over Helmut 2006-12-28 21:33
- Power in Diletti's sample size table Helmut 2007-01-01 23:59
  - Approximate Power Helmut 2007-01-06 15:17
    - Power Calculation for replicate crossover design mathews 2008-04-03 13:19
      - Power Calculation for replicate crossover design Helmut 2008-04-03 13:49
        
        Power Calculation for replicate crossover design mathews 2008-04-04 13:21
    - Exact Power Helmut 2009-09-25 19:20
      - Exact Power ElMaestro 2009-09-27 23:27
        
        Software validation Helmut 2009-09-28 15:21
        
        All the important answers are here! ElMaestro 2009-09-28 19:12
        
        All the important answers are here! Helmut 2009-09-28 19:52
        
        All the important answers are here! ElMaestro 2009-09-28 20:18
        All the important answers are here! yjlee168 2009-09-28 21:30
        
        All the important answers are here! Helmut 2009-09-28 23:18
        
        42! SASophylistic power oracle d_labes 2009-09-29 13:37
        
        Al Gore RhythmsHelmut 2009-09-29 14:52
        
        Al Gore Rhythms ElMaestro 2009-09-29 18:14
        Al Gore Rhythms yjlee168 2009-09-29 23:55
        
        All the important answers are here! yjlee168 2009-09-29 23:49
- R-Code for Power in 2×2 Cross-over KDA 2019-01-23 04:24
  - R-Code for Power in 2×2 Cross-over Ohlbe 2019-01-27 18:24
- R-Code for Power in 2×2 Cross-over Brus 2021-12-02 15:00
  - R-Code for Power in 2×2 Cross-over ElMaestro 2021-12-02 15:15
    - R-Code for Power in 2×2 Cross-over Helmut 2021-12-02 17:30
  - R-Code for Power in 2×2 Cross-over Helmut 2021-12-02 16:57