When I was a teenager I worked for one week at a local supermarket as a cashier. I only lasted a week because I found a “better” job at Tim Hortons. As it turns out it was probably a far worse job but it did have the advantage that when you worked the closing shift all the donuts would have to be thrown out. From time to time a clean garbage bag full of donuts would make its way into somebody’s car instead of the dumpster.  Anyway this article isn’t about how that is a great metaphor for illegally downloading music, its about incorrect metrics.

The supermarket, called Superstore, had a goal of getting people through the checkout as quickly as possible. This was a noble goal as nobody, except the English, likes spending time in a queue. They had identified that a checkout consisted of a few steps: unloading the cart, ringing the items up, paying, and packing. As this was a discount store the customer unloaded their own cart and packed their own groceries. The customer was typically the limiting factor on the speed of paying for the groceries too. This only left ringing the items up as an optimization point over which they had control.

superstoreAt the end of every shift we would be given a print out of the number of items a minute we were scanning. The goal was to spend no more than 2 second scanning an item so that you would end up with 30 items/minute as your average. These numbers were all rolled up and the store would report back to corporate with an average number. 30 items/minute seems pretty low for just passing a barcoded thing in front of the scanner. I had forgotten all about this metric until I was in a Superstore last week and they had left out a graph with the averages for that store.

22.45 items/minute.

I was greatly amused to see that the metric was still in force and even more amused to see the number was so low. See in my one week at the job I had averaged well over 30 items/minute, I think it was closer to 40 items/minute. It wasn’t because I was a cashier savant or because I entered into a transcendent state and became a scanning machine. It was because I knew how to game the system and break the metrics.

First I took advantage of the multiple items button. If you buy 10 tins of cat food the cashier is suppose to hit 10 QTY and then scan the item. This is a quick way to ring in many items and is designed to get people out of the store quicker: a great idea. However in the metrics it was only counted as one scan. If, instead, you scanned each item individually it would count as 10 items. I would scan the same item 10 times in rapid succession. In this way I could get 10 scans in about 4 seconds.

The second trick was the Total button. This is the button which is pushed at the end of the transaction and denotes moving from the ringing in phase to the payment phase. Because we cashiers couldn’t control the length of time a customer would take to pay us we weren’t measured on this phase. However you could get out of the payment mode and back into the ringing in mode by just pressing Exit. I took advantage of this by hitting the Total button any time I had an item with a code on it that I had to look up or a stack of items to move from one side of me to the other. It acted as a sort of pause button.

Any scanning averages they got from me were just about useless. What’s worse is that I was not at all optimizing for customer experience, I was optimizing for the benchmark.

Any time you set up key performance indicators(KPIs) in a business you have to be aware that in so doing you might not be optimizing for the things you want. You may very well be teaching people to optimize for your KPI. If your KPI is not very well thought out then the result could be a less efficient business process. I’m not saying don’t measure, measurement is key. What I’m saying is continually examine not just the results of your measurements but also the process you use to take measurements.