bear v1.0.0 - a data analytical tool for ABE in R [🇷 for BE/BA]

posted by yjlee168 Homepage – Kaohsiung, Taiwan, 2008-07-14 21:02 (6132 d 20:46 ago) – Posting: # 2030
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Dear Martin,

❝ I suggest that you may think about implementing a more sophisticated approach for estimation of the terminal elimination rate as currently only the last 3 data points are used:


At the beginning, when we planned how to calculate lambda in bear, we have looked for many options. The question is that there seems no "standard" method so far to calculate lambda. That's why we choose the last 3-point regression method. It's simple and easy to implement. It's just like that we use linear trapezoidal (LT) method to calculate AUC. Scientifically speaking, we all don't think that LT is as accurate as many others. In order to validate our results obtained from bear, we choose WinNonlin as the "reference" to compare.

❝ [...] lambda, the terminal phase rate constant, will be estimated from the slope of linear regression with the last three data points [...]

❝

❝ when using the OLS (ordinary least squares) criteria for estimation, the terminal elimination rate can be defined as a weighted sum of log-transformed concentrations where the weights are determined by the sampling schedule. in the case of a larger time gap between the last two measurement time points compared to the first two measurement time points, the concentration at the last time point is weighted more than the remaining two concentrations. this may lead to an inaccurate estimate of the terminal elimination rate when the last concentration is inaccurate for some reason (e.g. a higher inaccuracy of a bioanalytical method when dealing with values near to the limit of detection).


You're absolutely right. We will see what we can do about the sophisticated method to calculate lambda.

❝ more sophisticated and/or robust approaches for estimation of the terminal elimination rate are for example discussed in this post.


A very good pointer and references there. Many thanks.

All the best,
Yung-jin
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