## 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: $latex RI = \frac{a + b}{ { {n}\choose{2} } } &s=2$ where $$a$$ and $$b$$ are the number of times a pair…