The OSR is defned as:
$$
OSR = \frac{\sum_{i=1}^{I}\sum_{k=1}^{K}I(q_{ik}^{t} < q_{ik}^{s})}{I × K}
$$
where \(q_{ik}^{t}\) denotes the \(k\)th attribute of item \(i\) in the true Q-matrix (Q.true),
\(q_{ik}^{s}\) denotes \(k\)th attribute of item \(i\) in the suggested Q-matrix(Q.sug),
and \(I(\cdot)\) is the indicator function.