Pub. date: 2008 | Online Pub. Date: November 27, 2007 | DOI: 10.4135/9781412953948 | Print ISBN: 9781412928168 | Online ISBN: 9781412953948| Publisher:SAGE Publications, Inc.About this encyclopedia
Logistic regression is a statistical technique for analyzing the relationship of an outcome or dependent variable to one or more predictors or independent variables when the dependent variable is (1) dichotomous, having only two categories, for example, the presence or absence of symptoms, or the use or nonuse of tobacco (2) unordered polytomous, a nominal scale variable with three or more categories, for example, type of contraception (none, pill, condom, intrauterine device) used in response to services provided by a family planning clinic or (3) ordered polytomous, an ordinal scale variable with three or more categories, for example, whether a patient's condition deteriorates, remains the same, or improves in response to a cancer treatment. Here, the basic logistic regression model for dichotomous outcomes is examined, noting its extension to polytomous outcomes and its conceptual roots in both log-linear analysis and the general linear model. Next, consideration is given to methods ...