A big fat lie

I’ve previously written on the topic of lying with statistics, an easy though dishonest way to manipulate your marketing message because consumers assume if it has lots of specific numbers attached to it, it must be true.

This week we had a great example of statistical manipulation in the new report “F as in Fat: How Obesity Threatens America’s Future 2011” which was jointly issued by the prestigious Robert Wood Johnson Foundation and the noble-sounding Trust for America’s Health. Here’s the meat of it:

“Twenty years ago, no state had an obesity rate above 15 percent.  Today, more than two out of three states, 38 total, have obesity rates over 25 percent, and just one has a rate lower than 20 percent. “

My god, that’s shocking. No wonder newspapers and TV reporters coast to coast have picked it up more or less verbatim. But stop and think about it.

Suppose we went from zero obese states (which we’ll define as a state with an obesity rate over 20%) to 10 or 15 in that twenty-year period. That would be front page news. But this report said we went from zero to 49 states. From not a single state having a high obesity rate, to every state except one in this category.

Or, let’s look at super-obesity states (which we’ll define as a state with an obesity rate over 25%). Twenty years ago that definition would not have even registered, since every state but one was under 15%. Now two out of three states are in the mega-colossal, super-obese category.

Sure there are a bunch of fatties around. But don’t these statements seem simply incredible on the face of it?  Could it be that in those 20 years…..

…. Somebody had changed the definition of obesity?

And in fact, yes, that’s exactly what happened. In 1998 the National Institutes of Health introduced the Body Mass Index and 25 million Americans went from fit to fat overnight. They didn’t binge on salty snacks from dusk till dawn; their condition was simply the consequence of a change in the way overweight was defined.

I’m not saying obesity is not a problem. Of course it is. But look how easily the statistics can be manipulated and how hungrily the mass media will gobble them up.