The Dangers of Demographic Deception

I have already commented on the tendency of cities to think that they have been under-counted by the census--although there is never a complaint about over-counting. Mark VanLandingham, a demographer at Tulane University, has a very good Op-Ed piece in today's New York Times pointing out the dangers of over-estimating the population. 

Such overestimates have been especially problematic for New Orleans. According to the original census estimates for 2007, the city’s population stood at 239,124, which independent sources, like voter turnout and death records, indicate was a reasonable guess. But after heavy lobbying from then-Mayor Ray Nagin’s office — claiming the bureau’s methods missed large numbers of poor residents — the number was revised upward by about 20 percent, to 288,113.

A similarly successful challenge to the 2008 initial estimate led to yet another substantial uptick; combined, these revised estimates put the city on pace to recover almost all the residents it had lost after Hurricane Katrina within a few years.

Until, that is, the 2010 census count was released this year, showing the actual population size was almost 100,000 people smaller than what the revised numbers implied it should be — a psychological bucket of cold water thrown on a still-fragile city. The inflated estimates misled government, businesses and residents as they made life-altering decisions about where, when and how much to invest in the city’s recovery, and they diverted attention from some of the most serious problems that New Orleans was facing — and still faces — after the disaster.

VanLandingham notes, in particular, that the overestimation of New Orleans' population has allowed the city to ignore its very high murder rate.

The revised estimates of population size diluted the city’s murder rate, since a larger population results in fewer murders per capita. The lower rate may have stemmed some damage to tourism and investment; certainly the numbers allowed the government to spend its precious resources on items other than public safety. But in reality, they obscured the fact that in the years after Katrina, New Orleans had not only the nation’s highest murder rate, but a rate never before recorded for any American city.

This is a good reminder that you need to be careful what you ask for. An inflated population is not necessarily a good thing.