“The 80/20 Rule It’s so easy to get things out of proportion, but luckily there are also some easy solutions. Whenever I have to compare lots of numbers and work out which are the most important, I use the simplest-ever thinking tool. I look for the largest numbers. That is all there is to the 80/20 rule. We tend to assume that all items on a list are equally important, but usually just a few of them are more important than all the others put together. Whether it is causes of death or items in a budget, I simply focus first on understanding those that make up 80 percent of the total. Before I spend time on the smaller ones, I ask myself: Where are the 80 percent? Why are these so big? What are the implications? For example, here’s a list of the world’s energy sources, in alphabetical order: biofuels, coal, gas, geothermal, hydro, nuclear, oil, solar, wind. Presented like that, they all seem equally important. If we instead sort them according to how many units of energy they generate for humanity, three outnumber all the rest, as this graph shows.”