Hello everybody. I am using ltm package, an following this sequence: library(ltm)fit3 <- ltm(LSAT ~ z1)factor.scores(fit2, resp.patterns = rbind(c(0,1,1,0,0), c(0,1,0,1,0))) And I obtain the following result: Call:rasch(data = LSAT) Scoring Method: Empirical Bayes Factor-Scores for specified response patterns: Item 1 Item 2 Item 3 Item 4 Item 5 Obs Exp z1 se.z11 0 1 1 0 0 0 0.944 -0.959 0.8012 0 1 0 1 0 0 2.744 -0.959 0.801 I would like to know what is the meaning of the numbers Exp, z1 and se.z1 and if its possible to calculate the ability value of this two patters with those values. Thanks in advanced! Tony [[alternative HTML version deleted]]