Bioequivalence and Bioavailability Forum

Dear Detlew!

❝ ❝ Is this correct? I think that I screwed up the analytical error. Original text:

Analytical assay errors were generated from log-normal distributions with no bias, a CV of 10%, plus a constant term equal to the product of the assay CV and the limit of quantification, LQ.

❝ ❝ Shouldn’t I rather use a normal distribution instead (AErr1 <- rnorm(n=1, mean=0, sd=abs(C[j]*AErr)))? …

❝ I'm not quite sure If I really understand what you attempt here.

Well, reproduce the sims of the paper…

❝ But your implementation of the analytical error via log-normal distribution seems correct for me.

Really? Im not sure about meanlog=0 since dlnorm(1)==dnorm(0); shouldn’t I rather use meanlog=1?^*

❝ What I absolutely don't understand is the "... constant term ...". What is it good for . This is only a shift in the concentration levels constant over the whole curve and also for all simulated profiles the same, if I understand. But nothing like a random term as errors usually are deemed for.

Me too. I don't get the idea as well. Maybe it’s time to ask László.

❝ BTW: Why do you think you have screwed up something? Because the scatter in the simulated data is too smooth compared to real data .

Exactly. Also I don’t get the point why I should go with a log-normal here (noise is not necessarily positive). Analytical error is normal, IMHO.

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• No big difference: