Published by the Foundation for Open Access Statistics Editors-in-chief: Bettina Grün, Torsten Hothorn, Rebecca Killick, Edzer Pebesma, Achim Zeileis    ISSN 1548-7660; CODEN JSSOBK
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Authors: Achim Zeileis, Yves Croissant
Title: Extended Model Formulas in R: Multiple Parts and Multiple Responses
Abstract: Model formulas are the standard approach for specifying the variables in statistical models in the S language. Although being eminently useful in an extremely wide class of applications, they have certain limitations including being confined to single responses and not providing convenient support for processing formulas with multiple parts. The latter is relevant for models with two or more sets of variables, e.g., different equations for different model parameters (such as mean and dispersion), regressors and instruments in instrumental variable regressions, two-part models such as hurdle models, or alternative-specific and individual-specific variables in choice models among many others. The R package Formula addresses these two problems by providing a new class “Formula” (inheriting from “formula”) that accepts an additional formula operator | separating multiple parts and by allowing all formula operators (including the new |) on the left-hand side to support multiple responses.

Page views:: 8489. Submitted: 2009-09-23. Published: 2010-04-05.
Paper: Extended Model Formulas in R: Multiple Parts and Multiple Responses     Download PDF (Downloads: 5564)
Formula_1.0-0.tar.gz: R source package Download (Downloads: 1088; 308KB)
v34i01.R: R example code from the paper Download (Downloads: 1119; 2KB)

DOI: 10.18637/jss.v034.i01

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Paper: Creative Commons Attribution 3.0 Unported License
Code: GNU General Public License (at least one of version 2 or version 3) or a GPL-compatible license.