Once a full classification of the latter case was constructed
graphically, single samples were removed from the pre-classified
“training set” and re-introduced as unknowns. The sensitivity and
specificity for this study were calculated using the success rate of
the K-nearest neighbour algorithm in re-classifying individual
blind samples, given the rest of the samples as a training set. Each
individual sample was re-classified, with the result being com-
pared to the actual group it belonged to. A tally of true and false
positives/negatives was compiled, with overall numbers being
used to calculate sensitivity and specificity using Eqs. (5) and (6)
shown below (TP is true positive, FP is false positive, TN is true
negative and FN is false negative).