Conditional logistic regression: Difference between revisions

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Conditional logistic regression is an extension of [[logistic regression]] that allows to take into account [[stratification |stratification (clinical trials)|stratification]] and [[matching]]. Its main field of application is [[observational studies]] and in particular [[epidemiology]]. It was designed in 1978 by [[Norman Breslow]], [[Nicholas Day]], K. T. Halvorsen, Ross L. Prentice and C. Sabai.<ref>{{cite journal | author = Breslow, N. E., Day, N. E., Halvorsen, K. T., Prentice, R. L., & Sabai, C.| title = Estimation of multiple relative risk functions in matched case-control studies. | journal = American Journal of Epidemiology | date = 1978 | volume = 108 | issue = 4 | pages = 299-307 }}</ref> It is the most flexible and general procedure for matched data.

==Motivation==

Observational studies use stratification or matching as a way to control for bias. Several tests existed before conditional logistic regression for matched data as shown in the related tests section. However, they did not allow for the analysis of continuous predictors with arbitrary strata size. All of those procedures also lack the flexibility of conditional logistic regression and in particular the possibility to control for covariates.

Logistic regression can take into account stratification by having a different constant term for each strata.

==Conditional likelihood==

==Implementation==

Conditional logistic regression is available in R as the function clogit in the survival package. It is in the survival package because the log likelihood of a conditional logistic model is the same as the log likelihood of a Cox model with a particular data structure.<ref>{{cite web |url=https://stat.ethz.ch/R-manual/R-devel/library/survival/html/clogit.html |title=R documentation Conditional logistic regression |last1=Lumley |first1=Thomas |date= |website= |publisher= |access-date=November 3, 2016}}</ref>

==Related tests==

* [[Paired difference test]]

* [[Cochran-Mantel-Haenszel test]]

* [[McNemar test]]