Statistically significant ≠ clinically relevant! [General Sta­tis­tics]

posted by Helmut Homepage – Vienna, Austria, 2012-07-28 16:23 (3103 d 14:56 ago) – Posting: # 8989
Views: 4,758

Dear Hiren!

» But I am not geting how can we claim two formulation bioequivalent if there is significant formulation effect????

Statistically significant does not imply clinically relevant. In BE any [≥-20.00% & ≤+25.00%] difference (log-scale ±0.2231) generally* is considered irrelevant.

» Just on the basis that the variability of such difference will be less (narrow CI) how can we claim BE???

[image]Since the CI is within the acceptance range. BE is de­fined as ARlo ≤CLlo and CLhi ≤ARhi; nothing else. If we in­crease the sample size (keep­ing the CV constant) sooner or later any (!) formulation will show a statistically significant difference – if the PE ≠ 100%. Have a look at this slide: The minimum sample size according to many guidelines is 12. With T/R 0.95 and a CV of 15% we expect already a power of 83% (the CI will be 85.07 – 106.09%). With 48 sub­jects the upper CL drops below 100% and we will get a statistical significant difference (CI 90.27 – 99.98%).

Or, if we keep the sample size at 12 and our CV is even lower, the power will increase – and there­fore, also the chance to get a significant difference (exemplified by the light blue curve in the linked presentation). With a CV% of 10% power will be 98.8% and with 5% 99.99999995%. :-D

May I ask you for the sample size in your study?

Dif-tor heh smusma 🖖
Helmut Schütz

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