# ITEMAN2: Classical Item Analysis for Polytomous Items In ITEMAN: Classical Item Analysis

## Description

Classical Item Analysis for Polytomous Items

## Usage

 `1` ```ITEMAN2(data, options, ngroup = ncol(data) + 1, correction = TRUE) ```

## Arguments

 `data` a data frame with N rows and m columns, with N denoting the number of subjects and m denoting the number of items. `options` a vector of numerical code of the response categories available for the items such as c(0,1,2,3). The minumum score is assumed to be 0. `ngroup` number of score groups to be use for plotting the item trace lines `correction` TRUE or FALSE. If it is TRUE, then an adjustment is made for point-biserial correlation.

## Value

 `plots` a list object storing the item trace line plots for each item

## Author(s)

Cengiz Zopluoglu

`ITEMAN1` for classical item analysis of multiple-choice test items
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20``` ```data(timss2011_usa) timss2011_usa\$Q14B <- recode(var = timss2011_usa\$Q14B, recodes = "c(0)=3;c(1)=2;c(2)=1;c(3)=0") timss2011_usa\$Q14C <- recode(var = timss2011_usa\$Q14C, recodes = "c(0)=3;c(1)=2;c(2)=1;c(3)=0") item.analysis <- ITEMAN2(data=timss2011_usa, options=c(0,1,2,3), ngroup=18, correction=FALSE) item.analysis\$plots[[1]] # Item Trace Line for the first item # item.analysis\$plots[[2]] # Item Trace Line for the second item # item.analysis\$plots[[3]] # Item Trace Line for the third item # item.analysis\$plots[[4]] # Item Trace Line for the fourth item # item.analysis\$plots[[5]] # Item Trace Line for the fifth item # item.analysis\$plots[[6]] # Item Trace Line for the sixth item ```