Hello, I am submitting this mail to this address as it is the one provided in the gpls package for maintenance. I think I came accross a bug in the glpls1a.cv.error function in such package. This function calls the unexported function glpls1a.predict which is defined as follows: function (X, beta, family = "binomial", link = "logit") { if (all(X[, 1] == rep(1, nrow(X)))) { eta <- X %*% beta } else { eta <- cbind(rep(1, nrow(X)), X) %*% beta } return(h(eta, family, link)) } I.e., the function checks whether the first row in the new data is all ones (looking for an intercept maybe?) and if so, decides that X and beta are conformable. As I was applying a cv analysis, nrow( X ) was 1 and the first element in X was 1 just by chance for one observation (not an intercept) so the the wrong option was taken resulting in "non-conformable arguments" for matrix multiplication. Is there a safer way to check for intercepts other than comparing the first row to a vector of ones? Best regards, Carlos J. Gil Bellosta http://www.datanalytics.com