Bioequivalence and Bioavailability Forum • Exact Power

Exact Power [🇷 for BE/BA]

posted by Helmut – Vienna, Austria, 2009-09-25 21:20 (5320 d 01:55 ago) – Posting: # 4255
Views: 39,329

Dear all,

I made an investment and was able to compare results from R with the current version 7 of nQuery Advisor:*


+======+=====+===========+========+==========+

|  GMR |  n  |  R-code   | nQuery Advisor 7  |

+------+-----+-----------+--------+----------+

| 0.85 | 134 | 0.8017723 | 80.17  | 80.17722 |

| 0.90 |  38 | 0.8154940 | 81.54  | 81.54941 |

| 0.95 |  20 | 0.8346802 | 83.46  | 83.46802 |

| 1.00 |  16 | 0.8331980 | 83.32  | 83.32001 |

| 1.05 |  18 | 0.8001854 | 80.01  | 80.01854 |

| 1.10 |  32 | 0.8100682 | 81.00  | 81.00682 |

| 1.15 |  72 | 0.8042181 | 80.42  | 80.42180 |

| 1.20 | 294 | 0.8019247 | 80.19  | 80.19246 |

+======+=====+===========+========+==========+

nQuery requires sqrt(MSE) rather than CV as input = sqrt(ln(CV²+1)). The maximum precision is 6 decimal places. Therefore 0.1980422 rather than the value in full precision (0.1980422004353650284627675024887) like in R is used. But you see this value only if clicking the respective cell; both displayed and printed is 0.198042. nQuery gives power in percent with a maximum number of two decimal digits. That's a pity and values in the first column were the best one could get (display/print). If clicking in each cell power is given in percent to 5 decimal digits (7 significant digits); second column. It's clear that results are not rounded, but truncated. This looked weird first, but at least for power it makes sense.
Values agree nicely with the exception of a small discrepancy at GMR=1 (83.31980% vs. 83.32001%).
If I recall it correctly Dieter Hauschke wrote something about numerical problems in power estimation at T/R=1 in one of his papers.
:ponder:

I love validating software. :angry:

Janet D Elashoff
nQuery Advisor Version 7.0
Statistical Solutions, Cork, Ireland (2007)

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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 PowerHelmut 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 Rhythms Helmut 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