itemanalysis2 {itemanalysis}

Classical Test Theory Item Analysis for Polytomous Items

Description

Classical Test Theory Item Analysis for Polytomous Items

Usage

itemanalysis2(data, options, ngroup = ncol(data) + 1, correction = TRUE,
span.par=.3,verbose=T)

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.

span.par

a smoothing parameter to pass to ggplots when creating empirical ICCs

verbose

TRUE or FALSE. If it is TRUE, text output is printed.

Details

to be added later

Value

plots

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

item.stat

a matrix of basic item statistics

dist.sel

a matrix of distractor selection proportion statistics

dist.disc

a matrix of corrected point-biserial statistics for distractors

dist.disc

a matrix of corrected biserial statistics for distractors

Author(s)

Cengiz Zopluoglu

See Also

itemanalysis1 for classical item analysis of multiple-choice test items

Examples

 ## Not run: 
    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 <- itemanalysis2(data=timss2011_usa,
                                   options=c(0,1,2,3),
                                   ngroup=18,
                                   correction=FALSE)
                                   
    item.analysis$item.stat
      
    item.analysis$dist.sel
      
    item.analysis$dist.disc

    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
  
## End(Not run)