[R] Negative binomial GLM w/fixed dispersion parameter

Hello r-help, As the title suggests, I'm attempting to fit a negative binomial GLM with a fixed dispersion parameter. Both glm.nb() and glm(..., family=negative.binomial(theta, ...)) (using MASS) do not appear to allow this; upon specifying a value for theta, each then proceeds to re-estimate it.

[R] Grouping data via an index

Hello r-help, I have a lengthy vector of data (with values anywhere from 1-200), and another index vector of 'groups' representing values 0-2, 3-5, 6-8, ... of length 67. The index vector has the structure (1, 4, 7, ... , 196, 199), where each value is the midpoint of each respective group. I'm

Re: [R] Collapsing data frame; aggregate() or better function?

anada [EMAIL PROTECTED] -Original Message- From: jim holtman [mailto:[EMAIL PROTECTED] Sent: Thursday, September 13, 2007 6:49 PM To: Tobin, Jared Cc: [EMAIL PROTECTED] Subject: Re: [R] Collapsing data frame; aggregate() or better function? The second argument for aggregate is suppos

[R] Collapsing data frame; aggregate() or better function?

Hello r-help, I am trying to collapse or aggregate 'some' of a data frame. A very simplified version of my data frame looks like: > tester trip set num sex lfs1 lfs2 1 313 15 5 M23 2 313 15 3 F12 3 313 17 1 M01 4 313 17 2 F11 5 313 17