Editing Cluster analysis (section)

==== [[Jaccard coefficient|Jaccard index]] ====
The Jaccard index is used to quantify the similarity between two datasets. The [[Jaccard coefficient|Jaccard index]] takes on a value between 0 and 1. An index of 1 means that the two dataset are identical, and an index of 0 indicates that the datasets have no common elements. The Jaccard index is defined by the following formula:
<math>
J(A,B) = \frac {|A \cap B| } {|A \cup B|} = \frac{TP}{TP + FP + FN}
</math>
This is simply the number of unique elements common to both sets divided by the total number of unique elements in both sets.
Note that <math>TN</math> is not taken into account.