Message-ID: <1349662736.115.1632427488545.JavaMail.bigchem@cpu> Subject: Exported From Confluence MIME-Version: 1.0 Content-Type: multipart/related; boundary="----=_Part_114_1503220505.1632427488544" ------=_Part_114_1503220505.1632427488544 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Content-Location: file:///C:/exported.html Applicability domain assessment

Applicability domain assessment

The applicability domain assessment in OCHEM is based on the con= cept of distance to model, which was  introduced in T= etko, I.V. et al, J. Chem. Inf. Mod. 2008, 48(9), 1733-1746.

The following excerpt was taken from a doctoral work by Sushko (Sushko I= ., Applicability Domain of QSAR models. Doctroral work. 2011. http://mediatum.ub.tum.de/node?id=3D1004002)<= /p>

"Distance to model" definition

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The key abstract concept used in this work for assessment of AD is dista= nce to model (DM), defined as follows:

Distance to a model is any numerical measure of the prediction u= ncertainty for a given compound by the model.

A distance to model assesses how =E2=80=9Cfar=E2=80=9D is the compound f= rom the model. The compounds that are =E2=80=9Cfurther from the model=E2=80= =9D, which have larger values of DM, are by definition expected to have low= er prediction accuracy than compounds that have smaller values of DM. It sh= ould be clearly stated that prediction accuracy correlates

with DM only in average: for example, compounds with DM in range [0.5, 0= .6] will on average have higher prediction accuracy than compounds with DM = in range [0.6, 0.7] but, nonetheless, the prediction errors for some compou= nds from the first interval can be bigger than for some compounds from the = second interval. In other words, the key property of a DM is the discrimina= ting ability, i.e. the ability to discriminate predictions of high and low = accuracy. Importantly, DMs estimate the reliability of predictions. While a= ccuracy is an objective measure that has a rigid calculation procedure, rel= iability is subjective and can be estimated in numerous ways. Therefore, th= ere is a number of different DMs that assess the reliability of predictions= from different perspectives. Here, we briefly overview the DMs used for th= e AD assessment in this work.

http://mediatum.ub.tum.de/node?id=3D1004002&nb= sp;

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On the OCHEM web site the DM which covers 95% of compounds from th= e training set is used to define applicability domain of the model.

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