[R] Using pre-defined IRT parameters in ltm package

Hi all, I want to estimate scores using IRT when the model parameters are known. I'd like to define my parameters a priori using the ltm package, but haven't found much information on the manual. I appreciate any help on this. Thanks, Luana [[alternative HTML version deleted]] ___

[R] Simple loop question

Hi all, I'm trying to find out what is the equivalent in R for the following Stata code: Let's say I have the variables: a1, a2, a3, a4, a5 forvalues i = 1(1)5 { summary a`i' } That is, I want to know how to loop through variables in R. Thank you in advance, Luana [[alternative H

[R] Lmer binomial distribution x HLM Bernoulli distribution

ension of a binomial distribution. Is that right? If so, how can I adapt my R model to a Bernoulli distribution so that my R results are the same as my HLM results? Thank you so much, Luana Marotta [[alternative HTML version deleted]] __ R-help@r

[R] Sequence for repeated numbers

nce": Data: ID GradeSequence: 1 4 1 2 4 2 3 4 3 4 5 1 5 5 2 6 7 1 7 7 2 8 7 3 9 7 4 Any help is very much appreciate! Thank you, Luana Marotta [[alternative HTML

[R] reliability of the level-1 random coefficients (lme4)

level models. I tried to use the formula but I can't find specific information such as the sigma squared. Thank you, Luana Marotta [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/list

[R] Specify a minimum number of valid arguments for the mean function

Hello all, I want to specify a minimum number of valid arguments for the mean function--I have 5 variables but I want the mean only of cases that have at least 3 valid answers. What is the best way to do that? Thank you very much! Luana [[alternative HTML version deleted]]