My subject in this blog is language, but I’ve also been fascinated by the misuses to which statistics are put since high school, when I read Darrell Huff’s classic 1954 little book, How to Lie with Statistics. It was Huff who that taught me to look at graphs and bar charts to see whether they had been pruned at the bottom to exaggerate differences (in journalism and advertising, they almost always are).
I’ve just finished reading Charles Seife’s bestselling Proofiness: The Dark Arts of Mathematical Deception. It’s a fine survey of recent abuses of math in the public sphere, and I recommend it highly.
I don’t remember whether Huff deals with the phrase “fastest-growing,” but Seif doesn’t. Promoters of new sports, religious beliefs, types of business, and a huge variety of other things love to boast that they are the “fastest-growing” in their category. By this they mean to suggest that they are very popular.
This suggestion is mathematical nonsense because when even very unpopular activities begin growing they typically grow much faster proportionally than well-established ones.
A small software company just getting started can easily double its sales in a week whereas Microsoft never can. That doesn’t mean Microsoft needs to feel threatened by the newcomer.
If I invent a game to play all by myself today and then teach it to my friend to play it with me tomorrow, the number of people playing it will have increased by 100% overnight. I might plausibly argue that it’s the fastest-growing game in the country. But there are still only two people who know about it.
We need to know the relative size of two competitors to judge whether their different rates of growth mean anything. “Fastest-growing” is significant only when the competition is relatively close.
Most often, this sort of claim is not even backed up with statistics. It’s just a phrase people throw around when they feel their pet subject is not sufficiently widely recognized.
When you hear someone claim that something quite unexpected is the fastest-growing in its category, you can safely bet that it’s got little else to boast about statistically.