Rand Index versus the Adjusted Rand Index

I wrote about the Rand Index (RI) and the Adjusted Rand Index (ARI) in the last two posts but how do we interpret the indices and how are they different? The RI is: where $$a$$ and $$b$$ are the number of times a pair of items was clustered concordantly in two different sets. I wrote…

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The Rand index

I’ve been looking for ways to compare clustering results and through my searching I came across something called the Rand index. In this short post, I explain how this index is calculated.

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