# LMTEST: Stata module to perform Lagrange multiplier test after constrained maximum likelihood estimation

*Harald Tauchmann* ()

Statistical Software Components from Boston College Department of Economics

**Abstract:**
lmtest performs a Lagrange-multiplier (LM) test (Silvey, 1959), also referred to as a score test, of the restrictions that were previously imposed on the most recently estimated model by specifying the option constraints(). lmtest complements test and lrtest that implement the Wald test and the likelihood ratio test, respectively, which - together with the Lagrange-multiplier test - represent the three canonical approaches to testing hypotheses after maximum likelihood (ML) estimation (cf. Greene, 2012, p. 564). lmtest requires that the preceding estimation command allows the option constraints() and the maximization options iterate() and from(), and also requires that the constraints are saved in e(Cns) and the score vector is saved in e(gradient). Unlike test, the syntax of lmtest does not involve specifying the restrictions to be tested. The restrictions are rather specified by the option constraints() in the command syntax used for estimating the model. This corresponds to the logic of the Lagrange multiplier test to estimate only the restricted version of a model.

**Language:** Stata

**Requires:** Stata version 15

**Keywords:** Lagrange multiplier test; maximum likelihood; constraints (search for similar items in EconPapers)

**Date:** 2021-02-24

**Note:** This module should be installed from within Stata by typing "ssc install lmtest". The module is made available under terms of the GPL v3 (https://www.gnu.org/licenses/gpl-3.0.txt). Windows users should not attempt to download these files with a web browser.

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http://fmwww.bc.edu/repec/bocode/l/lmtest.ado program code (text/plain)

http://fmwww.bc.edu/repec/bocode/l/lmtest.sthlp help file (text/plain)

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