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)