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I'm clustering genes on gene expression data. Here's a hierarchically clustered heatmap using ward linkage and Euclidean distance

enter image description here

It clearly shows there are 5 or 6 clusters. Now when I evaluate their silhouette score on labels calculated from f_cluster, scipy. I get a decreasing curve like this

enter image description here

And increasing DB scores, although there is a slight dip at 4 to 5, 7 to 8 and 9 to 10 enter image description here

My question is : Should I take this curve as a "proof" that 5 or 8 clusters are better, even though the plot shows they are only relatively better than their neighbors? Or should I conclude that 2 clusters are best, even though heatmap shows otherwise? Why doesn't the heatmap translate to good scores on both the indices?

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  • $\begingroup$ The question is whether these clusters will validate on new data. I have my doubts. But on a practical levels the number of clusters is sometimes taken as the dimensionality with which you can relate the results to an outcome. At least when using clustering as unsupervised learning (data reduction). $\endgroup$ Feb 28, 2022 at 12:25
  • $\begingroup$ please read attentively this warning answer stats.stackexchange.com/a/63549/3277 $\endgroup$
    – ttnphns
    Mar 1, 2022 at 22:17

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