juniorK-Means Clustering

How do you choose the value of K in K-Means?

Updated May 16, 2026

Short answer

K is chosen using methods like the Elbow Method, Silhouette Score, or domain knowledge.

Deep explanation

The Elbow Method plots WCSS against K and selects the point where improvement slows. Silhouette Score measures how well-separated clusters are. Domain knowledge often provides constraints on expected groupings.

Real-world example

Segmenting users into 3–5 behavior groups in e-commerce.

Common mistakes

  • Choosing K arbitrarily without validation.

Follow-up questions

  • What is the Elbow Method?
  • What is Silhouette Score?

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