השוואת שיטות

	שיטת המרפק	מדד דייויס-בולדין (Davies-Bouldin Index)	אינרציה
תחום	הערכת מודלים	הערכת מודלים	הערכת מודלים
משפחה	MCDM	MCDM	MCDM
שנת המקור	1953	1979	1967
הוגה השיטה	Robert Thorndike	David L. Davies, Donald W. Bouldin	Stuart Lloyd, James MacQueen
סוג	Heuristic optimization criterion	Cluster quality metric	Clustering quality metric
מקור מכונן	Hastie, T., Tibshirani, R., & Friedman, J. (2009). The Elements of Statistical Learning: Data Mining, Inference, and Prediction. Springer Series in Statistics.	Davies, D. L., & Bouldin, D. W. (1979). A cluster separation measure. IEEE Transactions on Pattern Analysis and Machine Intelligence, 1(2), 224-227.	Lloyd, S. P. (1982). Least squares quantization in PCM. IEEE Transactions on Information Theory, 28(2), 129-137.
כינויים	elbow analysis, knee detection	DBI, Davies Bouldin index	WCSS, within-cluster sum of squares, cluster cohesion
קשורות	5	5	5
תקציר	The Elbow Method is a heuristic for selecting the optimal number of clusters in partitional clustering. Introduced by Robert Thorndike in 1953, it involves fitting clustering models for increasing numbers of clusters and plotting the within-cluster sum of squares (WCSS) against the number of clusters. The 'elbow' occurs where the rate of WCSS decrease sharply changes, suggesting an optimal cluster count.	The Davies-Bouldin Index, introduced by Davies and Bouldin in 1979, is a metric for evaluating clustering quality based on the average similarity between each cluster and its most similar neighboring cluster. Lower values indicate better clustering, with a minimum of 0 representing perfectly separated, non-overlapping clusters.	Inertia, also called Within-Cluster Sum of Squares (WCSS), is a measure of cluster cohesion that quantifies how tightly points are grouped around their cluster centroids. Lower values indicate more compact, cohesive clusters. Inertia is the primary objective function for k-means clustering and has been a fundamental metric since the method's introduction.