<?xml version="1.0" encoding="utf-8"?><!DOCTYPE article  PUBLIC '-//OASIS//DTD DocBook XML V4.4//EN'  'http://www.docbook.org/xml/4.4/docbookx.dtd'><article><articleinfo><title>FAQ/mlr</title><revhistory><revision><revnumber>5</revnumber><date>2019-08-13 11:19:47</date><authorinitials>PeterWatson</authorinitials></revision><revision><revnumber>4</revnumber><date>2019-08-13 11:14:10</date><authorinitials>PeterWatson</authorinitials></revision><revision><revnumber>3</revnumber><date>2019-08-13 11:09:38</date><authorinitials>PeterWatson</authorinitials></revision><revision><revnumber>2</revnumber><date>2016-11-11 09:31:04</date><authorinitials>PeterWatson</authorinitials></revision><revision><revnumber>1</revnumber><date>2014-01-21 14:53:32</date><authorinitials>PeterWatson</authorinitials></revision></revhistory></articleinfo><section><title>Multigroup logistic regression</title><para>Multinomial (or multigroup) logistic regression is a generalization of binary logistic regression applied to finding which variables best discriminate between three or more groups. It is available in most statistics software including SPSS. </para><para>The procedure produces regression estimates of form a(j) + b(kj) for the j-th group where a(j) is a constant term related to the relative sizes of the groups and b(kj) is the k-th predictor coefficient. As in ordinary (linear) regression a group predictor with s levels will be decomposed into s-1 dummy variables. For one of the groups, R, a(R) = b(kR) = 0 since group R is used as a reference group. R is usually taken to be the first or the last category.  </para><para>These regression estimates are then used to compute a score in each group for each individual of form a(j) + b(j)xi where xi is the score for individual, I in group j. The score for all individuals in group R is zero.  </para><para>The individual is then classified into the group for which they have the highest score.   </para><para><emphasis role="underline">Reference</emphasis> </para><para><ulink url="https://lsr-wiki-02.mrc-cbu.cam.ac.uk/statswiki/FAQ/mlr/statswiki/FAQ/mlr?action=AttachFile&amp;do=get&amp;target=MLR.pdf">Garson GD (2014) Logistic regression: binary and multinomial.</ulink> Statistical Associates Publishers:Asheboro, NC. This illustrated tutorial introduces multinomial logistic regression. Contains SPSS (and SAS) examples. This is a major revision of the 2012 and 2013 texts.  The attachment consists of the first 25 pages of text only.   </para></section></article>