Work out silhouette score instantly with clear inputs, formula shown and shareable results.
For one point, the silhouette compares a, its mean distance to the other members of its own cluster, with b, its mean distance to the members of the nearest other cluster. The score (b - a) / max(a, b) runs from -1 to 1: near 1 the point is comfortably inside its cluster, near 0 it sits on a boundary and negative values mean it would fit better elsewhere.
Silhouette coefficient
s = (b - a) / max(a, b)
Average the silhouette across all points for several values of k and take the k with the highest mean. Unlike inertia, the silhouette does not fall monotonically as k grows.
Very much. Silhouette values computed with Euclidean and cosine distance are not comparable, so fix the metric before comparing runs.