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Scree plot

As explained in Statistics Slam Dunk

A scree plot displays a quantity such as within-cluster variation against the number of clusters to help identify an appropriate cluster count.

A scree plot helps choose the number of clusters for K-means. It places candidate cluster counts on the x-axis and within-cluster sum of squares on the y-axis. section 11.5.2

Use the plot to identify the elbow:

  • Increase K and recompute within-cluster variation. section 11.5.2
  • Look for the bend where additional clusters produce diminishing reductions. section 11.5.2
  • Treat the elbow as guidance rather than a definitive answer, then compare it with silhouette analysis. section 11.5.2

NBA team clustering

A scree plot can compare K values from 2 through 7 when clustering standardized team payrolls and regular-season wins. The chosen K=4 solution separates the teams into four clusters. section 11.5.2

options(scipen = 000)
p3 <- fviz_nbclust(final_kmeans, kmeans, method = "wss") 
p4 <- fviz_nbclust(final_kmeans, kmeans, method = "silhouette")

Generate the within-sum-of-squares scree plot in R with fviz_nbclust(..., method = "wss"), alongside the silhouette diagnostic. section 11.5.2

How Statistics Slam Dunk covers it

How deep it goes
Explains axes, repeated variance calculations, elbow interpretation, and subjectivity, but defers detailed silhouette computation.
Examples
Uses NBA team payrolls and regular-season wins, comparing candidate K values from 2 through 7.
What it assumes
Assumes familiarity with K-means clustering and cluster counts, while defining within-cluster variation and the elbow interpretation.
What you can do after
Evaluate candidate cluster counts and choose a defensible K for K-means, while checking the elbow against silhouette results.
How it connects
Connects K-means clustering, the elbow method, within-cluster sum of squares, and average silhouette method.

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This explainer was generated by Manning's knowledge graph from the text of Statistics Slam Dunk. The section links point to the parts of the book it draws on.