ITEMAN (version 1.0)

ITEMAN2: Classical Item Analysis for Polytomous Items

Description

Classical Item Analysis for Polytomous Items

Usage

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

Details

to be added later

See Also

ITEMAN1 for classical item analysis of multiple-choice test items

Examples

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