Bioequivalence and Bioavailability Forum

α-inflation ≈ urban myth [General Sta­tis­tics]

posted by Helmut  – Vienna, Austria, 2013-01-09 19:07 (4121 d 12:02 ago) – Posting: # 9807
Views: 7,178

Dear Detlew!

❝ ❝ Same value if I switch lines 65–66 to R’s round().

❝ Your observation that cround() and round() work equal if rounded to 4 decimals.

Oh no! So we can abandon the 1 mio function calls and stick to round().

❝ power.sim2x2(CV=0.3, n=c(4,7), GMR=1.25)

I see. Didn’t understand your lines 6–7.

Now let’s see what I got for the extreme ’corners’ and the center of my grid. All sim’s with the same seed. Values in red are significantly >0.05…
                magical mystery code         my code          power.TOST
                rounded    unrounded   rounded    unrounded      exact
n 12, CV 0.06   0.049432   0.049839    0.050503   0.050331     0.050000
n 60, CV 0.06   0.050579   0.050231    0.050495   0.049924     0.050000
n 30, CV 0.25   0.050021   0.049946    0.050046   0.050309     0.050000
n 12, CV 1.0    0.000034   0.000034    0.000025   0.000019     0.000025
n 60, CV 1.0    0.001920   0.001913    0.001936   0.001858     0.001904
Rounding is evil – at least if we want to compare results with expected (theoretical) ones.

Extremely imbalanced sequences, where n₁+n₂=n from above. Arrows denote direction of the change compared to balanced cases.
                magical mystery code   power2.TOST
                rounded    unrounded      exact
 8/ 4, CV 0.06  0.049839↑  0.049981↑    0.050000–
40/20, CV 0.06  0.050558↓  0.050231–    0.050000–
20/10, CV 0.25  0.050017↓  0.049946–    0.049999↓
 8/ 4, CV 1.0   0.000017↓  0.000017↓    0.000014↓
40/20, CV 1.0   0.000548↓  0.000545↓    0.000554↓
Can’t see any relevant α-inflation – on the contrary (see esp. power(2).TOST). I think Martin ows my a beer. THX for the code; saved me two days of sim’s.

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


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Complete thread:

• Imbalanced Xovers: α-inflation? Helmut 2012-12-27 17:21 [General Sta­tis­tics] 
  • Imbalanced Xovers: α-inflation? ElMaestro 2012-12-28 09:30
    • Imbalanced Xovers: α-inflation? Helmut 2012-12-28 14:37
      • please explain ElMaestro 2012-12-29 08:44
        • I’ll try Helmut 2012-12-29 15:42
  • Imbalanced Xovers: α-inflation? d_labes 2012-12-31 13:50
  • One Mio sims of 2x2x2 in R in under 1 sec d_labes 2013-01-09 15:23
    • Wow! Helmut 2013-01-09 16:10
      • Unbalanced d_labes 2013-01-09 16:56
        • α-inflation ≈ urban mythHelmut 2013-01-09 18:07
          • Beer d_labes 2013-01-10 11:07
            • Beer Helmut 2013-01-10 13:45