I hope some of the authors of the package MCMCpack read this. I don't know if there is a way to set the response in the model formula of MCMClogit other than a (numeric) response vector. I think the MCMClogit in the MCMCpack needs some development so that the response in the formula could be set as a two-column matrix with the columns giving the numbers of successes and failures (just as in glm) or at least to be able to set the weights also when using the response vector. The advantage would be when analysing large datasets (over 1 million rows) to have it summarized and entered as a matrix because otherwise it takes a huge amount of memory space and crashes the program (if trying to expand the matrix into a response vector to have it in the formula. After all, the bayesian logistic regression is especially useful in large datasets. Is there a way to do that? Thanks -- View this message in context: http://www.nabble.com/Response-as-matrix-in-MCMClogit--tf3696522.html#a10336757 Sent from the R help mailing list archive at Nabble.com.