Bioequivalence and Bioavailability Forum

Dear Ohlbe!

❝ ❝ ❝ What most people do is that they only use one of the two replicates of the LLOQ and ULOQ samples. Usually the first replicate is used,…

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❝ ❝ Really most people?

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❝ In my experience, yes. I mean, most people analysing only the first and last samples in duplicate.

Ah, now I get your point!

❝ […] if you consider you need duplicate analysis to get a correct fit, then you should also analyse the subject samples in duplicate...

From a statistical point of view the best weighting scheme would be 1/s² (1/x or 1/x² are crude attempts to deal with multiplicative error). I don’t want to start a discussion whether it makes sense to calculate s² from n=2. But there is a drawback: 1/s² can only be used for pretty ‘stable’ methods where one would never drop any calibrator.

❝ Some other labs analyse the whole curve in duplicate, once at the start of the run and once at the end, to compensate for possible drifts. Personally if there is a drift I would rather shorten the run... But I think that's a discussion we had previously on the forum.

Yes…