Today's Census 2010 results have enormous implications for policy analysis in California. Most of the news will focus on redistricting and political implications, but the biggest impact could come through the effect on major policy analysis.
Since the last Census in 2000, a chasm has opened up between the annual population estimates for California issued by the Department of Finance (DOF) and the Census Bureau. The gap stood at about 1.5 million people, and was driven by differences in how the two demographic projections measure migration. Wonky types in the state have been debating this for years and have been waiting for today's once per decade enumeration to settle the dispute. Among researchers in the state, the majority such as Steve Levy's Center for the Continuing Study of the California Economy, state agencies, and the PPIC have projections that follow the Department of Finance; whereas our Center and others have believed annual Census Bureau estimates to be more accurate and have based our projections on these. (The difference is based on migration rates which Census estimates with addresses on IRS tax returns, whereas DOF primarily uses drivers license data.)
Since so many of our projects rely in part on population projections, I am pleased that the Census 2010 results released today closely match the projections we have been using. On a practical level, it saves a lot of work adjusting and reestimating models, and means we won't have to back track from conclusions drawn from them.
While some will moan that these estimates are bad for California since we won't gain Congressional clout, it is actually a win for California policy analysis to get away from the overly-high DOF population estimates. The DOF estimates and projections are being used to justify big public spending proposals such as a peripheral canal, dams, high-speed rail and more. Let's hope the Census numbers will finally get all the various analysts to revise down their demand projections to more realistic levels, and take a second look at these projects and see if they still make sense with fewer people to both use the services and pay the bill.
The first to fix their models should be the PPIC/Davis water wonks. As I pointed out over 2 years ago, they were exagerrating the already overstated CA DOF projections.