Use the Moneyball curve to determine what effect your labour has on sales and margins.
"Moneyball," the best-selling book and movie about the game of baseball revealed how data insights could determine which players contributed the most, rather than relying on hunches. This breakthrough way of looking at baseball players, also known as Sabermetrics can be applied to retail labour, too.
Many retailers use Sales Per Labor Hour (SPLH) to measure productivity. However, analysis shows this interpretation to be lacking and even misleading. It does not take into account employees' ability to generate revenue, repeat business and ultimately increase margin.