Bioequivalence and Bioavailability Forum

Not sure whether I understand this [Two-Stage / GS Designs]

posted by Helmut  – Vienna, Austria, 2012-10-23 19:17 (4625 d 22:27 ago) – Posting: # 9454
Views: 6,977

Hi ElMaestro!

❝ When we calculate type I errors and power in Potvin's scenarios we assume a T/R. This is a 'known', in contrast to the estimates we get from the sampled data.

Not quite. You are mixing two things up, IMHO. T/R is an assumption – not “known”. Hard-core statisticians told me that (even for a fixed design) we never should use term “sample size calculation”, but “sample size estimation” instead because T/R is assumed and CV an estimate at the best (or also only an assumption).

❝ When we calculate the sample size for the second stage we apply a known (=assumed) T/R and a measured variability,

Known ≠ assumed. We never know.

❝ but the measured variability reflects the sampled T/R.

Why? Variance is independent from a shift in location.

Too stupid for the rest of your post.

—
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:

• 2-stage maximum likelihood of CV/RMSE, given T/R ElMaestro 2012-10-22 15:06 
  • Not sure whether I understand this Helmut 2012-10-22 15:40
    • Not sure whether I understand this ElMaestro 2012-10-22 16:34
      • Not sure whether I understand this d_labes 2012-10-23 16:44
        • Not sure whether I understand this ElMaestro 2012-10-23 16:55
          • Not sure whether I understand thisHelmut 2012-10-23 17:17
            • Ach du lieber ElMaestro 2012-10-23 20:51