addDiscriminationIndex: Calculate Conventional Item Discrimination Index

In gadenbuie/mctestanalysis: Multiple Choice Test Analysis

Description

Calculates the conventional item discrimination index, based on complete test results only. Follows the formulation described in Lopez (1998), where item discrimination d = p(UG) - p(LG). UG and LG are the upper and lower groups – the upper and lower 27% of students as ranked by their overall test scores – and p(UG) and p(LG) are the proportion of correct answers in each group.

Usage

addDiscriminationIndex(mctd, percentile = 0.27)

Arguments

mctd	Existing mcTestAnalysis data object
percentile	Percentile defining upper and lower groups (standard is 0.27)

References

The Item Discrimination Index: Does it Work? Tristan Lopez A. Rasch Measurement Transactions, 1998, 12:1 p. 626. http://www.rasch.org/rmt/rmt121r.htm

gadenbuie/mctestanalysis documentation built on May 16, 2019, 5:34 p.m.