Hello, Could there be clarification added to glm's documentation? In contrast, glmnet leaves no ambiguity about what it expects for response. glm: y: is a vector of observations of length n glmnet: y: For family="binomial" should be either a factor with two levels, or a two-column matrix of counts or proportions (the second column is treated as the target class). For family="multinomial", can be a nc>=2 level factor, or a matrix with nc columns of counts or proportions. For either "binomial" or "multinomial", if y is presented as a vector, it will be coerced into a factor. "a vector of observations" doesn't really narrow it down much. The warning emitted when y a is vector of proportions isn't particularly informative, either. -------------------------------------- Dario Strbenac University of Sydney Camperdown NSW 2050 Australia