1. A method for sorting particles in a stream of a sample in a flow cytometer, comprising: (a) producing from a stable sort having desirable sort characteristics multiple images of a portion of said stream; (b) generating from said multiple images an averaged numerical reference standard representative of said stable sort; (c) continuously collecting during the sorting multiple running images of said portion of said stream; (d) generating from said multiple running images (c) at least one numerical sample average representative of the sample sort of each collection of said multiple running images; and (e) comparing each numerical sample average (d) to said numerical reference standard (b) and determining whether average (d) exhibits a deviation from said reference standard that requires an adjustment of said sort.