Dear R-helpers, let us assume, that I have the following dataset:
a <- rnbinom(200, 1, 0.5) b <- (1:200) c <- (30:229) d <- rep(c("q", "r", "s", "t"), rep(50,4)) data_frame <- data.frame(a,b,c,d) In a first step I run a glm.nb (full code is given at the end of this mail) and want to predict my response variable a. In a second step, I would like to run a glm.nb based on a subset of the data_frame. As soon as I want to predict the response variable a, I get the following error message: "Error in model.frame.default(Terms, newdata, na.action = na.action, xlev = object$xlevels) : factor d has new level(s) q" Does anybody have a solution to this problem? Thank you in advance, K. Steinmann (working with R 2.0.0) Code: library(MASS) a <- rnbinom(200, 1, 0.5) b <- (1:200) c <- (30:229) d <- rep(c("q", "r", "s", "t"), rep(50,4)) data_frame <- data.frame(a,b,c,d) model_1 = glm.nb(a ~ b + d , data = data_frame) pred_model_1 = predict(model_1, newdata = data_frame, type = "response", se.fit = FALSE, dispersion = NULL, terms = NULL) subset_of_dataframe = subset(data_frame, (b > 80 & c < 190 )) model_2 = glm.nb(a ~ b + d , data = subset_of_dataframe) pred_model_2 = predict(model_2, newdata = subset_of_dataframe, type = "response", se.fit = FALSE, dispersion = NULL, terms = NULL) ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html