I created a logistic regression model for the data set immediately below and obtained the following parameter estimates: Coefficients : Estimate Std. Error t-value Pr(>|t|) altc -0.064539 0.359398 -0.1796 0.8575 alts -0.287682 0.381881 -0.7533 0.4513 Then I reformatted the data so as not to repeat identical observations. The reformatted data set is near the bottom of this message. I cannot figure out how to run the logistic regression with the reformatted data. I have tried using a weight statement, but that has not solved the problem. Can anyone offer a suggestion? Thanks for any help. Mark Miller Gainesville, Florida # school program style count new.data <- matrix(c( 1, 1, "s" , 1, 1, 1, "s" , 1, 1, 1, "t" , 1, 1, 1, "t" , 1, 1, 1, "t" , 1, 1, 1, "t" , 1, 1, 1, "c", 1, 1, 1, "c", 1, 1, 2, "s" , 1, 1, 2, "s" , 1, 1, 2, "s" , 1, 1, 2, "s" , 1, 1, 2, "t" , 1, 1, 2, "t" , 1, 1, 2, "t" , 1, 1, 2, "t" , 1, 1, 2, "t" , 1, 1, 2, "t" , 1, 1, 2, "c", 1, 1, 2, "c", 1, 1, 2, "c", 1, 1, 2, "c", 1, 1, 2, "c", 1, 1, 2, "c", 1, 2, 1, "s" , 1, 2, 1, "s" , 1, 2, 1, "t" , 1, 2, 1, "t" , 1, 2, 1, "c", 1, 2, 1, "c", 1, 2, 1, "c", 1, 2, 2, "s" , 1, 2, 2, "s" , 1, 2, 2, "s" , 1, 2, 2, "s" , 1, 2, 2, "t" , 1, 2, 2, "t" , 1, 2, 2, "t" , 1, 2, 2, "t" , 1, 2, 2, "c", 1, 2, 2, "c", 1, 2, 2, "c", 1, 2, 2, "c", 1 ), nrow = 43, byrow = TRUE) new.data2 <- data.frame(new.data) names(new.data2) <- c("school", "program", "style", "count") new.data2$style <- as.factor(new.data2$style) levels(new.data2$style) library(mlogit) mldata <- mlogit.data(new.data2, varying=NULL, choice="style", shape="wide") mlogit.model <- mlogit(style ~ 1 , data = mldata, reflevel = "t") ; summary(mlogit.model) # school program style count new.data <- matrix(c( 1, 1, "s" , 2, 1, 1, "t" , 4, 1, 1, "c", 2, 1, 2, "s" , 4, 1, 2, "t" , 6, 1, 2, "c", 6, 2, 1, "s" , 2, 2, 1, "t" , 2, 2, 1, "c", 3, 2, 2, "s" , 4, 2, 2, "t" , 4, 2, 2, "c", 4 ), nrow = 12, byrow = TRUE) new.data2 <- data.frame(new.data) names(new.data2) <- c("school", "program", "style", "count") new.data2$style <- as.factor(new.data2$style) levels(new.data2$style) library(mlogit) mldata <- mlogit.data(new.data2, varying=NULL, choice="style", shape="wide") mlogit.model <- mlogit(style ~ 1 , data = mldata, reflevel = "t") ; summary(mlogit.model) -- View this message in context: http://n4.nabble.com/Logistic-regression-with-weights-tp1490450p1490450.html Sent from the R help mailing list archive at Nabble.com.