Re: [R] qu: predict with lmer (lme4) or other ways to get classification accuracy

I had to deal with this issue yesterday, and I'm guessing many who use lme4 have this same issue because of the lack of a predict.lmer function. It seems to me that one would need to plug the X %*% b output from the predict.lmerBin function below into the logistic distribution to get the actual p

Re: [R] For Social Network Analysis-Graph Analysis - How to convert 2 mode data to 1 mode data?

All, There is a simple solution to this problem using R's matrix algebra commands. I describe in detail at http://www.stanford.edu/~messing/Affiliation%20Data.html http://www.stanford.edu/~messing/Affiliation%20Data.html . Best wishes, -Solomon -- View this message in context: http://www

[R] Confirmatory factor analysis problems using sem package (works in Amos)

Hello all, I'm trying to replicate a confirmatory factor analysis done in Amos. The idea is to compare a one-factor and a two-factor model. I get the following warning message when I run either model: "Could not compute QR decomposition of Hessian. Optimization probably did not converge." I h

[R] Brightness readings for part of an image

Hi R users, I am doing some image analysis and I'd like to know if anyone knows of: 1. a way to specify a rectangle (using xy coordinates) within an image to have R evaluate using xy pixel coordinates and 2. a way to get brightness readings for that part of the image. If there's some way to c