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# What is the Accuracy?

The Accuracy is a performance metric that tells you the fraction of the predictions that were correct, without distinguishing between positive and negative predictions. The Accuracy can be a very misleading metric when the data set is unbalanced (when the prevalence is either very high or very low).

The Accuracy can be calculated as follows:

\frac{TP + TN}{TP + TN + FP + FN} = \frac{TP + TN}{P + N}