# irtstudy: Item Response Theory Study In talbano/epmr: Tools for Educational and Psychological Measurement

## Description

Functions for estimating item response theory item and person parameters.

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```irtstudy(x, model = 1, complete = FALSE, ...) rirf(ip, theta = seq(-4, 4, length = 100)) riif(ip, theta = seq(-4, 4, length = 100)) rief(ip, theta = seq(-4, 4, length = 100)) rtrf(ip, theta = seq(-4, 4, length = 100)) rtif(ip, theta = seq(-4, 4, length = 100)) rtef(ip, theta = seq(-4, 4, length = 100)) irtsim(ip, theta) ```

## Arguments

 `x` matrix or data.frame of scored item responses, one row per person, one column per item. `model` integer for the number of paramters to estimate per item. The default of 1 specifies item intercepts or difficulties via the Rasch model, 2 additionally specifies item slopes or discriminations, and 3 additionally specifies varying lower asymptotes. `complete` logical with default `FALSE` indicating whether or not `x` should be reduced to rows with complete data across all columns. `...` further arguments passed to or from other functions, including `glmer` `ip` vector or matrix of item parameters, with a in the first column, b in the second, and c in the third. `theta` vector of thetas over which to estimate the corresponding function.

## Examples

 ```1 2 3 4 5 6``` ```ritems <- c("r414q02", "r414q11", "r414q06", "r414q09", "r452q03", "r452q04", "r452q06", "r452q07", "r458q01", "r458q07", "r458q04") rsitems <- paste0(ritems, "s") pisagbr <- PISA09[PISA09\$cnt == "GBR", rsitems] irtgbr <- irtstudy(pisagbr) ```

talbano/epmr documentation built on May 31, 2019, 2:51 a.m.