SAS/R code of MSD method for comparing dis­so­lution [Dissolution / BCS / IVIVC]

posted by wligtenberg – The Netherlands, 2016-12-12 15:09 (2663 d 23:24 ago) – Posting: # 16839
Views: 21,475

First of all thank you for this very useful post!
I hope you are still active, or that other can help me out with this as well.

I have tried to use your code and verify it against the article and so far I have been unable to get the same results.
I think you have a typo in the definition of your mr. You have a value: 78.45, where in the article I think it is: 78.54.
Interestingly, with this typo, you get exactly the same value as in the article on page 6.

And then I started to see if some calculations might have been off, and I checked the mean values calculated with the mean values in the Tsong article.
And mean values calculated in your script are off compared to the ones reported:
tbar
[1] 23.08000 39.61333 49.73333 57.19000 68.05333 84.12000 92.48000 96.43667
rbar
[1] 46.77167 60.13333 67.27500 71.98667 78.08500 84.81667 89.09333 91.43833


TEST MEAN 23.08 37.95 49.73 57.19 68.05 84.12 92.48 96.34
REFERENCE MEAN 46.77 60.21 67.28 71.97 78.05 84.82 89.09 91.43

Even if this could be related to rounding issues, which I think is impossible. Look at the following values:
mean(mt[, 2]) = 39.61 versus 37.95 in the article.
Even if I add 0.01 to all values (or subtract it) I don't get that value:
mean(mt[, 2] + 0.01)
[1] 39.62333
mean(mt[, 2] - 0.01)
[1] 39.60333


Similar thing with the covariance matrices, if I use your data (with typo) I get results that are more similar (excluding some rounding errors) to the Tsong article, than without the typo.
Which is uncanny, so maybe I missed a memo where this is a known typo, and that you actually used the correct data.
(which however does not explain why the mean values are off, in the article)

I just wanted to verify my implementation before I am going to put it into practice.
I might even create a package out of this in the end, because I think it would be nice to have an R package with a couple of methods combined.

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