tia {irtoys}

Elementary test-item analysis

Description

Elementary analysis of the items in a test and the test sumscores based on Classical Test Theory.

Usage

tia(choices, key, ...)

Arguments

choices

The original responses to the items in the test: persons as rows, items as columns. May contain NA.

key

A vector containing the key (correct answers) to the items in choices. If not given, the function will check if all data are either 0, 1, or NA: if yes, NA are recoded as 0, else an error message is returned.

...

Other parameters that may be passed to sco or cov

Value

A list with three elements:

testlevel

A list of statistics at test level (currently, only Cronbach's alpha, may be extended in future)

itemlevel

A matrix showing, for each item, the proportion of correct responses, the correlation with the sum score, and the alpha that the test would have if the item were dropped.

optionlevel

A matrix showing, for each possible choice in the multiple-choice item, the proportion of responses given, and the correlation with the sum score for the test (including the item). The correct response is highlighted with asterisks.

Author(s)

Ivailo Partchev

Examples

itemsum <- tia(Unscored, key=c(2,3,1,1,4,1,2,1,2,3,3,4,3,4,2,2,4,3))