Editing Partition coefficient (section)

===Atom-based===
Standard approaches of this type, using atomic contributions, have been named by those formulating them with a prefix letter: AlogP,<ref name="Ghose_1986"/> XlogP,<ref>{{cite journal | vauthors = Cheng T, Zhao Y, Li X, Lin F, Xu Y, Zhang X, Li Y, Wang R, Lai L | title = Computation of octanol-water partition coefficients by guiding an additive model with knowledge | journal = Journal of Chemical Information and Modeling | volume = 47 | issue = 6 | pages = 2140–8 | year = 2007 | pmid = 17985865 | doi = 10.1021/ci700257y | url = http://www.sioc-ccbg.ac.cn/?p=42&software=xlogp3 }}</ref> MlogP,<ref name="Moriguchi_1992"/> etc. A conventional method for predicting log ''P'' through this type of method is to parameterize the distribution coefficient contributions of various atoms to the overall molecular partition coefficient, which produces a [[parametric model]]. This parametric model can be estimated using constrained [[Least squares|least-squares]] [[estimation theory|estimation]], using a [[training set]] of compounds with experimentally measured partition coefficients.<ref name="Ghose_1986">{{cite journal | vauthors = Ghose AK, Crippen GM | title = Atomic Physicochemical Parameters for Three-Dimensional Structure-Directed Quantitative Structure–Activity Relationships I. Partition Coefficients as a Measure of Hydrophobicity | journal= Journal of Computational Chemistry | volume= 7 | issue= 4 | pages = 565–577 | year= 1986 | doi = 10.1002/jcc.540070419  | hdl = 2027.42/38274 | s2cid = 4272062 | url = https://deepblue.lib.umich.edu/bitstream/2027.42/38274/1/540070419_ftp.pdf | hdl-access = free }}</ref><ref name="Moriguchi_1992">{{cite journal | vauthors = Moriguchi I, Hirono S, Liu Q, Nakagome I, Matsushita Y | title = Simple method of calculating octanol/water partition coefficient | journal = Chem. Pharm. Bull. | volume=40 | issue = 1 | pages = 127–130 | year = 1992 | doi = 10.1248/cpb.40.127 | doi-access = free }}</ref><ref name="Ghose_1998">{{cite journal | vauthors = Ghose AK, Viswanadhan VN, Wendoloski JJ | title = Prediction of Hydrophobic (Lipophilic) Properties of Small Organic Molecules Using Fragmental Methods: An Analysis of AlogP and ClogP Methods | journal = Journal of Physical Chemistry A | volume = 102 | issue = 21 | pages = 3762–3772 | year = 1998 | doi = 10.1021/jp980230o | bibcode = 1998JPCA..102.3762G }}</ref> In order to get reasonable correlations, the most common elements contained in drugs (hydrogen, carbon, oxygen, sulfur, nitrogen, and halogens) are divided into several different atom types depending on the environment of the atom within the molecule. While this method is generally the least accurate, the advantage is that it is the most general, being able to provide at least a rough estimate for a wide variety of molecules.<ref name="Moriguchi_1992"/>