The following video is from our Dec. 6 edition of MarketFoolery. In it, Joe Magyer drops some knowledge on investors everywhere by revealing a crucial metric he uses when analyzing retailers: revenue per employee.

While it's not an end-all-be-all number that will tell you when to buy or sell a stock, it is oftentimes closely correlated with how well those companies turn over their inventory. 

Chris Hill and Joe Magyer own shares of Amazon.com. Rich Greifner owns none of the stocks mentioned. The Motley Fool owns shares of Amazon.com and Costco Wholesale. Motley Fool newsletter services recommend Amazon.com and Costco Wholesale. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.