John Hood: Why Numbers Matter in Political Debate
RALEIGH — I promise I’m no math geek. So why do my columns about North Carolina politics and public policy so often feature rankings, economic data, or other statistics?
Because if you’re going to write seriously about these topics, you’ve got to pay attention to numbers. While we tend to form our deepest political convictions in response to upbringing, relationships, and emotionally compelling stories, we often decide what we think about a specific issue, and especially how pressing we think it is, in response to statistical claims made by political actors.
Are the rich getting richer and the poor getting poorer? Do conservatively governed states grow faster than progressively governed states? Is North Carolina one of the stingiest places in the country when it comes to paying teachers? Is the University of North Carolina system floundering or improving?
These are clearly matters of intense public interest in our state. They are also empirical claims. They can’t be evaluated based on anecdotes or political slogans.
We’re all prone to cognitive biases, of course, including the tendency to select as valid the statistical evidence that confirms our prior beliefs while ignoring or denigrating any statistical evidence to the contrary. That we all feel this temptation is not, however, a good reason to revert to bumper-sticker nostrums and mutual contempt. It’s a good reason to read widely, study carefully, and engage constructively.
If you sincerely hope to persuade others that their factual claims are mistaken, you have to be open to the risk that your factual claims may turn out to be mistaken. No need to worry, though. You don’t have to surrender your core beliefs to entertain this possibility — because, let’s face it, your core beliefs probably weren’t formed by a statistical claim in the first place!
Consider the case of economic mobility. Virtually everyone believes it should be easier for people born into poverty to work their way out of it. Disagreements arise when we get more specific about the extent of the problem, its primary causes, and the best ways to remedy them.
Eight years ago, the findings of a new academic study set off a firestorm in North Carolina’s largest city. Researchers found that among the nation’s 50 most-populous metropolitan areas, Charlotte ranked precisely 50th in economic mobility. Shocked, local leaders responded with meetings and task forces and new initiatives. More broadly, as North Carolina took a rightward turn under a GOP-controlled General Assembly, critics often pointed to Charlotte’s dead-last ranking as evidence that too many folks in our state were still being left behind.
Well, the study was later updated and refined. Thanks to fantastic reporting on its findings by local radio station WFAE, we have a much-clearer sense of what the data really show about economic mobility — and why its measurement is so complicated. Mobility remains a real problem, of course. But Charlotte (and, by implication, North Carolina as a whole) should never have been labeled as last in the nation. By some measures, it’s closer to the average.
For example, when measuring income disparities or mobility or growth over time, should we focus on individual income or household income? The original mobility study focused on the latter. It’s understandable — we all live in a household, after all, whether it be a single-person household or a married couple with many children.
Still, if you divide income by households rather than by persons and then track the figures over time, your measure won’t just reflect changes in income received. It will also reflect changes in family structure. If a married couple is earning $50,000 and then divorces, you go from one $50,000 household to two households with average earnings of $25,000. A 50% drop in average income? Kinda, but such a claim is very easy to misinterpret.
When it comes to measuring complex realities, there will never be a single set of statistics that everyone accepts as gospel. We’re going to keep arguing about them. I look forward to it.
John Hood is a John Locke Foundation board member and author of the novel Mountain Folk, a historical fantasy set during the American Revolution (MountainFolkBook.com).
