Calculates the within cluster spread
recordWithinClusterSpread(sampleIDs, dim_subset = NULL, SubpopSizeFilter)
A vector of sample names.
a string vector of string names to subset the data columns for PAC; set to NULL to use all columns.
threshold to filter out very small clusters with too few points; these very small subpopulations may not be outliers and not biologically relevant.
Returns the sample within cluster spread