ctitem {classicaltest} | R Documentation |
Classical test theory item statistics
Description
Calculates several item statistics, including: item means, frequencies, proportions, and correlations between item responses and the total score.
Usage
ctitem(
x,
key,
navalue = NA,
wt = NULL,
itemcategories = NULL,
administered = NULL,
itemscores = NULL
)
Arguments
x |
a data frame or matrix. |
key |
a vector or a list indicating the keys to score the data. If answers can only be right or wrong use a vector. If partial credits are allowed, use a list where the first element contains the keys for full credits, and next elements contain progressively the partial credit information. If a test has a combination of full credit and partial credit items, leave the full credit items as NAs in the keys for partial credit. |
navalue |
a single value indicating the score of NAs. |
wt |
a vector with total weights. Default is |
itemcategories |
a vector indicating all the possible categories for all items. If NULL, possible categories will be derived from data. |
administered |
a logical matrix indicating which items were administered.
The dimensions should be the same as |
itemscores |
a numeric vector indicating all the possible scores for all items.
If |
Value
A list.
Examples
# Data preparation
## Random weights creation
set.seed(1919)
wt <- sample(x = 1:4, size = nrow(dichodata), replace = TRUE)
# Item analysis for multiple choice items
ctitem(x = dichodata, key = dichokey, itemcategories = c('A','B','C','D'), wt = wt)