ItemStatistics {exametrika}R Documentation

Simple Item Statistics

Description

This function calculates statistics for each item.

Usage

ItemStatistics(U, na = NULL, Z = NULL, w = NULL)

Arguments

U

U is a data matrix of the type matrix or data.frame.

na

na argument specifies the numbers or characters to be treated as missing values.

Z

Z is a missing indicator matrix of the type matrix or data.frame

w

w is item weight vector

Value

NR

Number of Respondents

CRR

Correct Response Rate denoted as $p_j$.

ODDs

Item Odds is the ratio of the correct response rate to the incorrect response rate. Defined as o_j = \frac{p_j}{1-p_j}

Threshold

Item Threshold is a measure of difficulty based on a standard normal distribution.

Entropy

Item Entropy is an indicator of the variability or randomness of the responses. Defined as e_j=-p_j \log_2 p_j - (1-p_j)\log_2(1-p_j)

ITCrr

Item-total Correlation is a Pearson's correlation fo an item with the number of Number-Right score.

Examples

# using sample dataset
ItemStatistics(J15S500)

[Package exametrika version 1.1.0 Index]