Power parallel group: PowerTOST/SAS/PASS [🇷 for BE/BA]

posted by d_labes  – Berlin, Germany, 2015-08-14 12:29 (3467 d 13:33 ago) – Posting: # 15263
Views: 12,371

Dear Helmut,

❝ Occasionally slight differences for the parallel design example.


As you might imagine: that makes me (as a nitpicker) a little bit nervous.
But of course I trust in my software even if I myself had written it. I only don't trust in any computers :cool:.
Fired up my beasty beast [image].
Used the prudish beauty :-D
Proc Power;
  twosamplemeans
  test=equiv_ratio
  power=.           /* means we solve for power */
  alpha=0.05
  meanratio=1 1.05
  npergroup=50 150 250 350 450 550
  cv=1.5
  lower=0.8
  upper=1.25
  ;
run;


Let's look at the results (5 decimals, PASS 14 from your link):
                                             ------ power ------
  N1  N2    N   R1 COV  RL   RU Alpha  PowerTOST    SAS    PASS14   PASS12(help) PASS12(calc)
  50  50  100 1.00 1.5 0.8 1.25  0.05   0.00000   0.00000  0.00000    0.0000     0.00000
 150 150  300 1.00 1.5 0.8 1.25  0.05   0.10488   0.10488  0.10488    0.1049     0.10488
 250 250  500 1.00 1.5 0.8 1.25  0.05   0.48431   0.48431  0.48431    0.4843     0.48431
 350 350  700 1.00 1.5 0.8 1.25  0.05   0.71606   0.71606  0.71704    0.7170     0.71704
 450 450  900 1.00 1.5 0.8 1.25  0.05   0.84896   0.84896  0.84945    0.8494     0.84945
 550 550 1100 1.00 1.5 0.8 1.25  0.05   0.92185   0.92185  0.92208    0.9221     0.92208     
  50  50  100 1.05 1.5 0.8 1.25  0.05   0.00000   0.00000  0.00000    0.0000     0.00000
 150 150  300 1.05 1.5 0.8 1.25  0.05   0.09731   0.09731  0.09731    0.1010 (!) 0.09731
 250 250  500 1.05 1.5 0.8 1.25  0.05   0.43421   0.43421  0.43421    0.4360 (!) 0.43421
 350 350  700 1.05 1.5 0.8 1.25  0.05   0.63561   0.63561  0.63661    0.6366     0.63661
 450 450  900 1.05 1.5 0.8 1.25  0.05   0.75960   0.75960  0.76018    0.7602     0.76018
 550 550 1100 1.05 1.5 0.8 1.25  0.05   0.83925   0.83925  0.83961    0.8396     0.83961

Note especially the differences between help page and actually calculated for PASS12.

Victory all a long the line :thumb up:! PowerTOST must be correct because SAS says so :-D.

"Enjoy the best sample size software on the market" (PASS12 startup screen).

Power: That which statisticians are always calculating but never have.
Guernsey McPerson's "The Devil's Drug Development Dictionaries"

Regards,

Detlew

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