From: Gavin Simpson <gavin.simpson_at_ucl.ac.uk>

Date: Thu 18 Jan 2007 - 16:34:04 GMT

Date: Thu 18 Jan 2007 - 16:34:04 GMT

On Thu, 2007-01-18 at 20:00 +0530, Ajay Narottam Shah wrote:

> Folks,

*>
**> The betareg package appears to be polished and works well. But I would
**> like to look at the exact formulas for the underlying model being
**> estimated, the likelihood function, etc. E.g. if one has to compute
**> \frac{\partial E(y)}{\partial x_i}, this requires careful calculations
**> through these formulas. I read "Regression analysis of variates
**> observed on (0,1): percentages, proportions and fractions", by
**> Kieschnick & MucCullogh, `Statistical Modelling" 2003, 3:193-213. They
**> say that the beta regression that they show is a proposal of theirs -
**> is this the same as what betareg does, or is this the Standard
**> Formulation?
*

If you want to know, the best place to look is the source code for the package, available as a tar.gz file from all good CRAN Mirrors.

I suggest this as the Windows binary might not contain the original source (i.e unprocessed with comments etc) - I forget now exactly how the binaries on that platform differ.

*>
*

> What else should I be reading about beta regressions? :-)

The reference cited in the References section of ?betareg would also be a good start, esp to understand what the betareg package is doing and how it compares to the other ref you cite.

**HTH
**
G

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