Thanks to Kit Baum an update of the -betafit- package is now available
on -ssc-. In the new version it is possible to use -predict- to get
predicted proportions, standard deviations, and Pearson residuals.
Also, -betafit- now uses better starting values, so in most cases it
will converge quicker. To update type -ssc install betafit, replace- or
-adoupdate, update-.
-betafit- deals with dependent variables that are constrained between
zero and one (primarily proportions) by fitting a beta distribution. It
can use two parameterizations: one in terms of two shape parameters,
and one in terms of a location and a scale parameter. The former
(called the conventional parameterization) corresponds to conventional
representation of the beta distribution in the literature and is
primarily useful in cases without explanatory variables, while the
latter (alternative parameterization) can model how the mean proportion
changes as the explanatory variables change, and is thus particularly
usefull in cases with covariates. -betafit- is written by Nick Cox,
Stephen Jenkins, and Maarten Buis.
-- Maarten
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
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