Re: QSAR - Modeling biological data

On 6 Feb 2003 at 9:09, Suzanne Sirois wrote:

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>
> Hello,
> I would like to develop a QSAR model using calculated descriptors as well as experimental values. The problem with the experimental values is the range. They are from 2 to 128 mg/ml. But some could not be determined and they are said to be > 128 mg/ml. How can I take into account in my training
set of data that are greater than.
>
> Thank you with your help
>
>
> Suzanne Sirois, Ph.D
> Cheminformatics, Computational Chemistry
>
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Hello,

if some of your experimental descriptors have only values of the type > 128 mg/ml
you have the following options:

- Eliminate the corresponding compounds from your training set. If calculations
show that this particular descriptor is of no importance for the biological activity to
be considered, the eliminated compounds can, of course, again be included.

- Do not use this descriptor.

- It might also be possible to derive some model for this descriptor which would then
allow to estimate the missing values.

I do not know what your measured values are. Since, however, drugs act on a molar
and not on a mass basis a correction with the molecular weight might be necessary.

Best regards

Rainer Franke

-- 
Prof. R. Franke / Dipl.-Chem. A. Gruska
Consulting in Drug Design GbR    phone: +49-33397-62396
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