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Re: advan8 vs. advan13

From: nonmem
Date: Sun, 01 Nov 2009 13:04:42 +0000 (GMT)

It seems like advan8 has integration difficulties when both LAG time and variability in Ka are implemented. Method=IMP has dificulties when advan8 has integration difficulties. Instead if reporting issues, it keeps running. The objective function is very low even when bioavailability is almost zero. Removing LAG and eta of Ka may fix it.

----- Original Message -----
From: nonmem
Date: Sunday, November 1, 2009 12:04 am
Subject: [NMusers] advan8 vs. advan13
To: nmusers

> Hello NONMEM users,
>
> Because advan13 was recomended for both stiff and nonstiff
> differential equations, I used it for stiff differential
> equations. It appeared that some results looked too sensitive
> to a parameters representing a "slow" processes. I did not
> observe it with nonmem6. When I used advan8, the objective
> function changed from 10228.853 (the final value; diagnostic
> plots looked good) to 5512.594 (the first value; I im still
> waiting for the final value of the objective function).
>
> Does it mean that advan13 should be used with caution when the
> equations are stiff or advan13 cannot replace advan8?
>
> Thanks,
> Pavel
>

Received on Sun Nov 01 2009 - 08:04:42 EST

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