ClustEval clustering evaluation framework
The Specificity relates the number of true negatives to the total number of false elements. This estimates a likelihood of an element being negative, if it is indeed negative. This measure is based on the pairwise approach to calculate TP,TN,FP and FN. $Specificity = \frac{TN}{TN+FP}$ In the binary classification background we have two classes that we want to distinguish: positive and negative. In this scenario there are four possible outcomes: