I just ran into a problem with residuals.glm() for GLMs fitted with glm(..., y = FALSE) For such fits, the residuals of type "deviance", "pearson" and "response" can't be computed (see example below). The reason is that residuals.glm() uses y <- object$y which obviously can't work for such fits. I've checked ?glm and ?residuals.glm and did not find it mentioned explicitely...looks like a bug to me. Best, Z ## example for poisson GLM from ?glm d.AD <- data.frame(treatment = gl(3,3), outcome = gl(3,1,9), counts = c(18,17,15,20,10,20,25,13,12)) glm.D93 <- glm(counts ~ outcome + treatment, family = poisson, data = d.AD, y = FALSE) ## residuals cannot be computed residuals(glm.D93, type = "deviance") residuals(glm.D93, type = "pearson") residuals(glm.D93, type = "response")