Thursday, March 24, 2011

Overestimates or Undercounts? Does this mean Detroit didn't lose quite so many people?

When the 2010 census count for New York City came out today, it struck me as a little light.  So I decided to compare the 2009 population estimates for the ten largest cities in the country againt that 2010 counts.  In all cases expect San Diego, the census count was lower than the 2009 estimate.  The average difference was four percent, which is four years of population growth at the national growth rate.  Here are the numbers: the first column of numbers is the 2009 estimate; the second is the 2010 count.  What is going on here?

New York City8,391,8818,175,133
Los Angeles 3,831,868 3,792,621
Chicago 2,851,268 2,695,598
Houston 2,257,9262,099,451
Phoenix 1,593,6591,445,632
Philadelphia 1,547,2971,526,006
San Antonio 1,373,6681,327,407
San Diego 1,306,3001,307,402
Dallas 1,299,5421,197,816
San Jose 964,695945,942