What Is Silhouette Score in Clustering?

Silhouette score is a metric used to measure the quality of a clustering algorithm’s performance. It is used to assess how well the data points within a cluster are related to each other, and how well they are separated from points in other clusters. The Silhouette score ranges from -1 to +1, with higher scores indicating better clustering performance.

The Silhouette score is calculated using two main factors: cohesion and separation. Cohesion measures how close the data points within a cluster are to each other.

It is calculated by finding the mean distance between all pairs of points within a cluster. Separation measures how far apart the data points in different clusters are from each other. It is calculated by finding the mean distance between all pairs of points in different clusters.

The Silhouette score takes into account both cohesion and separation when assessing the quality of a clustering algorithm’s performance. If there is high cohesion but low separation, or vice versa, then this will be reflected in the Silhouette score. For example, if all data points in a cluster are very close together but they are not distinctly separated from those in other clusters, then this will result in a low Silhouette score as there is not enough distinction between the clusters.

In addition to evaluating clustering algorithms, Silhouette scores can also be used to determine optimal number of clusters for unsupervised learning models. This can be done by calculating Silhouette scores for different values of k (the number of clusters) and selecting the one with highest score as the optimal value for k.

Conclusion: Silhouette Score is an important metric used to measure how well a clustering algorithm performs, by taking into account both cohesion and separation of data points within and across different clusters respectively. It can also be used to determine an optimal number of clusters for unsupervised learning models.