Remember the map that said $100 buys you the least in DC? That’s not the whole story

Sometimes, the eye-catching statistic isn’t really all that good.
In July, a map showing the relative value of $100 in states across the country made the news rounds. It caught local news attention in D.C. because of the dubious honor the city was awarded: The place where $100 is effectively worth the least.
That map, from the Tax Foundation, is reproduced below:

The map, and the statistics included therein, didn’t get much scrutiny from D.C. sources back in July. Perhaps because the District is, indeed, an expensive city so the numbers lined up with our own biases this time.
But, in an article published on Thursday in Greater Greater Washington, Kate Rabinowitz, of DataLensDC fame, said there’s two problems with the Tax Foundation map. “While it’s true $100 will buy you less in DC, it’s misleading to leave it at that,” she writes. Why?
Well, the first reason is something the Tax Foundation actually solved itself, about a week later. In the (in)famous map above, D.C. is compared to other states like California or Mississippi or Nebraska. The problem with this is that these states are all a meld of rural and urban areas, while D.C. is almost exclusively urban. “D.C. is wholly urban, and urban areas tend to be more expensive,” Rabinowitz writes. “A more accurate view would compare DC to other cities.”
And indeed, when the Tax Foundation rated the relative value of $100 across U.S. metro areas, D.C. was demoted to the seventh-most expensive.
But this isn’t the only problem Rabinowitz saw in the eye-catching “$100 buys you the least in D.C.” statistic. The main issue: this statistic doesn’t take income into account.
“In other words, while $100 might buy you a different amount of goods in one place versus another, what about the fact that you can make $100 a lot faster in some places than others?” Rabinowitz writes.
So Rabinowitz created her own map — one that shows personal income. And while yes, D.C. is still expensive, relatively high personal income goes at least part of the way toward explaining why. Read on for more in her Greater Greater Washington piece here.
Thanks for the context, DataLensDC, we appreciate all kinds of methodological critique.