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joyjac ★ Philippines, 2008-10-08 03:52 (6463 d 19:11 ago) Posting: # 2488 Views: 4,835 |
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Dear colleagues, Concurrent to our efforts in calculating the sample size for the BE of fixed dose combination preparations, may I request for your opinion/insight on how best to determine the sample size needed to achieve the desired power of the study, particularly, if one active drug is identified or reported in the literature as highly variable (intra-subject CV >30%) and the other active drug is not highly variable. Thanks for the kind help. |
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Helmut ★★★   Vienna, Austria, 2008-10-08 09:58 (6463 d 13:05 ago) @ joyjac Posting: # 2490 Views: 3,916 |
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Dear Joy, I'm afraid your sample size has to be calculated for the one drug with higher variability. If there's a large difference in variability between drugs, I would suggest to analyze only a neccessary subsample for the drug with lower variability (let's say the first 24 out of a total of 64). In analyzing just a subsample you avoid chances for a significant treatment effect (the stupid '100%-not-included-in-confidence-interval-question')... If the study is to be performed in more than one group - which is likely - the subsample should consist of subjects coming from all groups. Of course the planned procedure must be described in detail in the protocol, otherwise the impression of cherry picking may arise. — Dif-tor heh smusma 🖖🏼 Довге життя Україна! ![[image]](https://static.bebac.at/pics/Blue_and_yellow_ribbon_UA.png) Helmut Schütz ![[image]](https://static.bebac.at/img/CC by.png) The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
Ing. Helmut Schütz