ItemStatistics: Simple Item Statistics
Description
This function calculates statistics for each item.
Usage
ItemStatistics(U, na = NULL, Z = NULL, w = NULL)
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.
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
Examples
Run this code# using sample dataset
ItemStatistics(J15S500)
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