("Watch out," they must be thinking. "Here comes the crazy business professor!")
Anyway, it turns out that the firm raised some prices, kept some the same, and lowered others. The price of a 12-ounce regular coffee fell from 1.65 to 1.50. The 16-ounce coffee rose from 1.80 to 1.90, and the 20-ounce rose from 1.95 to 2.10.
On a per-ounce basis, things work out like this:
Under the old pricing, the first 12 ounces cost 13.75 cents per ounce. Now those ounces cost 12.5 cents per ounce.
Under the old pricing, the next 4 ounces cost 3.75 cents per ounce. Now those ounces cost a whopping 10 cents per ounce.
Under the old pricing, the next 4 ounces cost 3.75 cents per ounce. Now those ounces cost 5 cents per ounce.
This is a really interesting illustration of second-degree price discrimination. For this pricing to make sense, the firm must have decided that the weak economy and increased competition has made consumer demand for the first few ounces more elastic, but made the residual demand curve (that is, the demand for additional ounces past the first 12) less elastic.
It would be cool to know what data the firm used to come to these conclusions, but I think any MBA ought be to able to at least sort out how you'd design an experiment to measure these elasticities.
I also learned that many customers were quite upset by this pricing change. Apparently there was some yelling at employees (who, of course, had nothing whatsoever to do with the decision to raise prices), and more than a few angry phone calls to the district manager.
So I managed to learn some cool economics, even standing in a coffee shop. The whole conversation was nearly as entertaining as the time that two biz-economist friends of mine and I wandered into a shoe store in Maine (long story) and managed to get a really interesting lesson in mystery shopping and performance evaluation in retail.