Making Numbers Count: The Art and Science of Communicating Numbers

Human beings have trouble understanding numbers. Our brain haas a basic number system of one, two, three, four, five, and a lot. Distinguishing between the various "a lot"s is a challenge. This book focuses on the best ways to do it.

Humans can hold about 7 numbers, give or take a few in memory. Rounding numbers helps us to include numbers in memory. Comparing 10,000 and 4,000 can easily be stored in memory. 10,273 and 4,164 are much more challenging. Even better is reducing numbers to smaller human scale numbers. Instead of 10,000 to 4,000, a ratio of 5 to 2 is a much better scale. We also have great difficulty comparing big numbers (like a million and a billion). Making it into stories of smaller numbers helps the point. (Spending 50,000 a day, it would take 20 days to spend $1 million, but more than 50 years to spend $1 billion.)

An even better step is to relate the numbers ot something that people would understand. Florence Nightingale mastered this in advocating improved medical conditions. Statistics of improved soldier mortality rates were augmented with  comparisons to wartime mortality. Things seemed much more real when expressed in additional men killed in battle.

Comparing large numbers to items that people understand makes them even more real. The "understanding" can depend on the audience. For covid-19, different places would use different terms to express appropriate social distancing. "One surfboard" is more real than "6 feet". (However, some places got a little too cute with numbers like "1.5 mountain bikes.)

Another example was using analogy to express the size of the Evergiven that blocked the Suez canal. Ths ship is a quarter mile long. However, this is not a length we commonly understand. Calling it "as long as the Empire State Building laying on its side makes the distance much more relatable."

Knowledge of how the brain understands numbers can help make communication of ideas much more powerful. However, to be successful, the underlying story must be valid. (Stories of "Bezos earns enough to buy a car every second" sounds powerful. However, would you also say that this month as Amazon stock fell he lost the equivalent of two Teslas every second?) By having solid numbers with a good story we can get our point across best.