Re: Distribution of CWRESI as a diagnostic
Hi Rik,
In some investigations that Joakim Nyberg and I did at PAGE a while back, we
saw that CWRESI were less likely to be N(0,1) even if the model is correct,
compared to CWRES (Nyberg, Bauer, Hooker, PAGE, 2010). So I might recommend
creating the plot with CWRES. Otherwise, you could do multiple
simulation-evaluations with the model that you have to get an empirical
understanding of the expected CWRESI distribution, if the model you are
currently using was the model that generated the data. This could be done using
the “simeval” tool in NONMEM and “tricking” PsN into thinking that the CWRESI
are actually the CWRES by setting (CWRES=CWRESI) in the table file (not tested,
but I suspect this will work).
On a side note, I think my NMUSERS account is associated with my old “farmbio”
email address, so maybe you could forward this to note to NMUSERS?
Best regards,
Andy
Andrew Hooker, Ph.D.
Professor of Pharmacometrics
Dept. of Pharmacy
Uppsala University
Box 580, 751 23, Uppsala, Sweden
Phone: +46 18 471 4355
https://katalog.uu.se/profile/?id=N4-631
https://katalog.uu.se/profile/?id=N4-631
http://www.farmbio.uu.se/research/researchgroups/pharmacometrics/
Quoted reply history
On 15 Nov 2022, at 09:53, Rik Schoemaker
<[email protected]<mailto:[email protected]>> wrote:
Dear all,
I have routinely generated a histogram of CWRESI residuals as a model
diagnostic, expecting the standard deviation to be close to one, and then
commenting 'the SD is close to one as would be expected in a well behaved
model'. However, I have now run into a situation where the SD is 0.887 which I
consider a lot lower than I'd expect, but I have no clue what that tells me...
Any ideas? Should I stop making the plot? ;)
Kind regards,
Rik
Rik Schoemaker, PhD
Occams Coöperatie U.A.
Malandolaan 10
1187 HE Amstelveen
The Netherlands
http://www.occams.com/
+31 20 441 6410
[email protected]<mailto:[email protected]>
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