The correct response rate (CRR) is one of the most basic and important
statistics for item analysis. This is an index of item difficulty and
a measure of how many students out of those who tried an item correctly
responded to it. This function is applicable only to binary response data.
The CRR for each item is calculated as:
$$p_j = \frac{\sum_{i=1}^n z_{ij}u_{ij}}{\sum_{i=1}^n z_{ij}}$$
where \(z_{ij}\) is the missing indicator and \(u_{ij}\) is the response.
Usage
crr(U, na = NULL, Z = NULL, w = NULL)
# S3 method for default
crr(U, na = NULL, Z = NULL, w = NULL)
# S3 method for binary
crr(U, na = NULL, Z = NULL, w = NULL)
Value
A numeric vector of weighted correct response rates for each item.
Values range from 0 to 1, where higher values indicate easier items
(more students answered correctly).
Arguments
U
Either an object of class "exametrika" or raw data. When raw data is given,
it is converted to the exametrika class with the dataFormat function.
na
Values to be treated as missing values.
Z
Missing indicator matrix of type matrix or data.frame. Values of 1 indicate
observed responses, while 0 indicates missing data.
w
Item weight vector specifying the relative importance of each item.