Lies, damned lies, and statistics

Mark Vanlandingham has an opinion piece in The New York Times about the problems of overstating population:

A city's population size is more than just a number: it determines how many representatives it can send to the state legislature and Congress, and it often determines how much money it receives from state and federal programs. Bigger cities, and faster-growing cities, tend to attract more business investment, professional sports teams, and public attention. Not surprisingly, cities pay a lot of attention to the Census Bureau’s annual population estimates, which take place between the decennial censuses. And when these come in lower than expected, many will fight hard to revise them upward— 39 cities and towns successfully challenged their 2008 estimates alone. But, because the process is so politicized, it often results in significant overestimates. While local governments and civic boosters might cheer such an outcome, population overestimates can ultimately lead to a dangerous misallocation of scarce public resources.
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 twenty 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.
Several of us living in the city, who were monitoring its repopulation rates, knew these figures were implausible. And yet city hall cheered the results. Until, that is, the 2010 census count was released this year, showing the actual population size was almost one hundred thousand 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.
Take, for example, the homicide 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.
Had the Census Bureau held firm on its original estimates, the singularity of our murder morass would have been apparent, and we would have been better positioned to marshal the local, state, and national resources required to fight it. An inability to effectively monitor our city’s population has likewise hampered New Orleans’s efforts to plan for our future health care needs, education needs, and other essential services. Consultants have found, for example, that a hospital under construction is larger than needed for the number of people who actually live there.
Such over-adjustments are not limited to New Orleans. Of the 38 other successful challenges to census estimates in 2008, 78 percent resulted in a figure that now appears to have been too high.
No one should fault a city for cheering its own recovery, and cities should be free to challenge estimates that they suspect are too low; indeed, many challenges are initially correct. But the process has become politicized in a way that favors short-term interests: cities are often less concerned about getting the number right than in getting the number higher, leaving the resulting problems to subsequent administrations to sort out. Moreover, the Census Bureau is led by appointees without fixed terms, making them vulnerable to political pressure.
One immediate solution, then, would be to appoint bureau directors for five-year terms, which would help ensure that population figures are based on scientific evidence and would help limit political influence from elected officials, their constituents and special-interest groups. Doing otherwise is no favor to the local jurisdiction requesting an uptick. The day of reckoning always comes, and in the meantime, cities like New Orleans are left without the data needed to direct scarce resources toward their most pressing problems.

As Strother Martin said in Butch Cassidy: Morons, I'm surrounded by morons...