The tyranny of small decisions is the challenge we face when many individual decisions, when taken together, result in an outcome that is suboptimal or that the group as a whole doesn’t want.

Say you’re at a restaurant with friends and early on there’s a plan to split the bill. Your thoughts of a cheap night evaporate with the knowledge that just getting a salad makes little difference if others are getting martinis and appetizers. Heck, if you’re paying for those anyway why not get a dessert? And so a group will often pay more when splitting the bill. It’s also an example of the tyranny of small decisions.

Named in a paper by the Cornell economist Alfred E. Kahn, he also discussed the example of the passenger services on the Ithaca railroad. The many daily decisions of people choosing to drive or fly rather than travel by train ended with a train route that was no longer viable and closed, even though each person may have actually wanted to keep a train option.

Similar ideas to the tyranny of small decisions include the tragedy of the commons, the Abilene paradox, and local optimisation.

The tyranny of small decisions

There's an old story about the statistician who drowned after seeing that the average depth was 3ft. Averages, or in this case the mean, necessarily hide some data, but very often they also hide what's really going on.

Let's say you run a delivery service and have an average delivery time of one day, it could be that most deliveries are actually a few hours while a few particular ones have people waiting for a week. Or a figure of average incomes might hide that most people have low salaries and a few are millionaires. But just looking at the average you can't tell. Sometimes a different measure of central tendency, like the median, can provide a clearer picture.

Sheldon Zedeck, a UC Berkeley psychology professor who taught me about the design of experiments, gave wise advice: spend time with your data. Sometimes it's the only way to know what's happening for sure.

Sneaky averages

Banner clouds can form on the side of a high or exposed peak and seem to stick to the mountain face like a banner, even on an otherwise cloudless day. There are several theories for how they form but in general strong winds of cold dry air from one side likely interact with warmer humid air on the other. Look out for them next time you're in the mountains.

Also see lenticular clouds, thunder clouds, and more clouds.

Get my new weekly sketch in your inbox

Banner cloud