On allele frequency computation from DNA typing data

Forensic applications of DNA typing data require the estimation of the frequencies of all observed alleles, which is currently done by a fixed set of groupings (binning) of alleles in a database. Recently it's validity has been questioned on the ground that when a DNA fragment size is close to a bin boundary, the frequencies of all adjacent bins should be added. On the contrary, the current forensic database indicates that when the match window of a DNA fragment overlaps 2 bins, it is enough to consider the bin with the larger frequency, and this never underestimates the frequency within the match interval with the current choice of fixed-bin widths. On average, the current fixed-bin procedure yields an allele frequency at least 2-fold higher than that of a floating-bin.