data item accuracy Philippe Rocca-Serra Rand accuracy Rand index adapted from wikipedia: https://en.wikipedia.org/wiki/Accuracy_and_precision#In_binary_classification last accessed: May 2016 in the context of binary classification, accuracy is defined as the proportion of true results (both true positives and true negatives) to the total number of cases examined (the sum of true positive, true negative, false positive and false negative). It can be understood as a measure of the proximity of measurement results to the true value.