Simple matching coefficient

The simple matching coefficient (SMC) or Rand similarity coefficient is a statistic used for comparing the similarity and diversity of sample sets. Given two objects, A and B, each with n binary attributes, SMC is defined as: SMC = number of matching attributes total number of attributes = M 00 + M 11 M 00 + M 11 + M 01 + M 10 {\displaystyle {\begin{aligned}{\text{SMC}}&={\frac {\text{number of matching attributes}}{\text{total number of attributes}}}\\[8pt]&={\frac {M_{00}+M_{11}}{M_{00}+M_{11}+M_{01}+M_{10}}}\end{aligned}}} where M 00 {\displaystyle M_{00}} is the total number of attributes where A and B both have a value of 0, M 11 {\displaystyle M_{11}} is the total number of attributes where A and B both have a value of 1, M 01 {\displaystyle M_{01}} is the total number of attributes where A has value 0 and B has value 1, and M 10 {\displaystyle M_{10}} is the total number of attributes where A has value 1 and B has value 0.

Source: Wikipedia — Simple matching coefficient (CC BY-SA 4.0)