Abundance sorting
Abundance sorting is used for clustering when more more abundant sequences make better centroids. This is often the case, for example, in 16S OTU clustering of next-generation sequencing reads. In this case, more abundant sequences are likely to be accurate biological sequences while rare or singleton reads are more likely to contain sequencing errors or be due to PCR artifacts such as chimeras.

It is generally recommended that sequences are globally trimmed before clustering and abundance sorting.