Bioequivalence and Bioavailability Forum • Sample size for a pilot study to estimate the CVintra

Sample size for a pilot study to estimate the CVintra [Power / Sample Size]

posted by Helmut – Vienna, Austria, 2010-03-02 03:19 (5953 d 01:13 ago) – Posting: # 4848
Views: 16,450

Hi ElMaestro!

❝ 4 to 6 in a pilot trial sounds like it may result in a CV_intra that is too poorly estimated. There are no rules, and 'poorly' is in this regard purely my personal subjective unqualified view.

No, 'poorly' is not purely your personal view, but qualified by the table from my previous post. Part:


 n  10%   15%   20%   30%   40%   50%

 6  15.6  23.6  31.6  48.2  65.8  84.8

16  12.2  18.3  24.4  36.9  49.5  62.5

If we calculate a CV_intra of 20% in the pilot (n=6), the upper 80% CL of the CV_intra is 31.6%. In other words there is a 20% chance that the CV might even be higher than 31.6%. If the pilot study study is larger (n=16), the estimated CV gets more reliable (=less uncertain) with 24.4%.

You are right with the sequential designs. If I don't have a lot (!) of previous data, I made them already my new standard.

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

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes

Complete thread:

Sample Size BA/BE Sriraj 2010-02-26 14:32 [Power / Sample Size]
- Sample Size BA/BE Helmut 2010-03-01 14:00
  - Sample size for a pilot study to estimate the CVintra yjlee168 2010-03-01 19:25
    - Sample size for a pilot study to estimate the CVintra Helmut 2010-03-01 21:01
      - Sample size for a pilot study to estimate the CVintra yjlee168 2010-03-01 23:47
        
        Sample size for a pilot study to estimate the CVintra Helmut 2010-03-03 19:04
        
        Sample size for a pilot study to estimate the CVintra yjlee168 2010-03-04 22:35
      - 80% confidence ? d_labes 2010-03-19 13:02
        
        75% confidence... Helmut 2010-03-19 14:12
    - Sample size for a pilot study to estimate the CVintra ElMaestro 2010-03-01 22:23
      - Sample size for a pilot study to estimate the CVintra yjlee168 2010-03-02 00:02
      - Sample size for a pilot study to estimate the CVintraHelmut 2010-03-02 02:19
        
        Sample size for a pilot study to estimate the CVintra yjlee168 2010-03-29 13:27
        
        Sample size for a pilot study to estimate the CVintra ElMaestro 2010-03-29 13:39
        
        Sample size for a pilot study to estimate the CVintra yjlee168 2010-03-29 13:47
        
        Sequential designs (history and future) Helmut 2010-03-29 14:19
        
        Sequential designs (history and future) yjlee168 2010-03-29 19:19
        
        Sequential designs (history and future) Helmut 2010-03-29 20:43
        
        Sequential designs (history and future) yjlee168 2010-04-01 18:58
        
        Sequential designs (WinNonlin vs. bear) Helmut 2010-04-02 21:00