 Simple matching coefficient

For binary vectors, this similarity counts agreements on both presences and absences. Its complement is the normalized Hamming distance. Whether joint absences should count as similarity depends on the application; rare-presence data may call for a different coefficient.

The Simple Matching Coefficient (SMC) is a statistic used to measure the similarity between two sets or binary vectors. It provides a way to quantify the degree of similarity based on the presence or absence of certain characteristics. For binary vectors \( A \) and \( B \), each of length \( n \): - \( a \) is the number of features that are present in both \( A \) and \( B \) (i.e., both vectors have a value of 1).