I am running a kmeans on a sample size of 1000 data. The data is scaled (z).
When I run kmeans(df, nstart=25, centers=5)- it runs and I can get the size of each cluster. The largest group has 620 in it.
I ran it again (I did not mean to), but noticed the largest cluster then had 450 in it.
Out of interest, I kept trying and got the largest cluster to be anywhere between 450-800.
Now I know that the initialization can effect the clusters and cluster sizes. HOWEVER, I am surprised it varies so much. If my cluster sizes changed by 10-20, then I would get it. But these are large swings.
Of course I can set.seed to stop it- but it seems too odd to get that wide variation of results.
It seems too random that I might get the largest cluster of 450 or 600 or 775 based on when I ran it (or where it initialized). I feel uncomfortable with the results now.
Thoughts or explanations.