Bioequivalence and Bioavailability Forum

Dear all,

Please read carefully because I afraid my poor English make someone misunderstand.

Thanks for all comments that try to explain me or even speak to me sarcastically. I would like to reply in all issues but I am exhausted to explain them in English, so I will reply only issue of combined CV. I am sorry and I afraid my opinion will bother someone again. I have read the pooling of CV in Helmut's lectures around three week ago, the concept was developed using sampling distribution of sample variance from classical statistics or parametric approach. I appreciated Helmut because he understands and be able to apply statistical concept even if he does not grow up in statistical field, while I am as a statistician but I never try to apply that concept and excuse from them by "I am being busy" always.
Although I fully agree that concept, but not at all and I still stand that the pooling of CV concept is an option under some situations. Anyone can choose their own CV as long as they want to. It is quite subjective and there are many different reasons to support their own CV. There are pro and con in each way, for example, Mary select the minimum CV because she is optimistic and she trust that paper, Ronaldo exclude some CV before he pool the rest because those were studied in Thailand and he doesn’t trust them, Lady K. select the average CV because it's very simply, Kim select 25% CV because of his sponsor, Filipe M. select 14% CV because it is his team solution, Tom select the maximum one because he is conservative and he has a lot of budget…
Though the pooling of CV concept would be developed from statistical knowledge, it has some disadvantages. First, it does not simplify. Second, in case that one value of many CV is an outlier CV. Last and very important, as everyone knows this concept comes from assumption of parametric statistics, so each variance as samples or random variable (RV) should be iid from chi-square distribution. Are there anyone check them? How much its robustness if it breaks the assumptions? Are there any methods to combine them if it's not come from the same population? And bla bla bla… No need to answer these questions. Because I only want to elucidate my idea and I don't intent to insult the pooling of CV.

Finally, I would like to say sorry again to d_labes or anyone if my opinion bothers you and seem to be irrespective to the pooling of CV.

Sincerely,
Boonchai L.