I'm really curious how a "private sector demographic firm" has access to "tentative Census data" absent a leak. Either Politico is misrepresenting a private group's estimates as linked to the official census or... well I don't have an "or," I think that's it. Not that this doesn't have some value.
http://www.palmbeachpost.com/news/state/florida-could-get-two-new-congressional-seats-939157.html
EDS annually does reapportionment estimates based on the mid-year Census Bureau estimates released in December, projected forward to 2010. April 2010, The most recent report shows estimates using different projection intervals, and includes spreadsheets.
http://www.electiondataservices.com/images/File/NR_Appor09wTables.pdf
So ESRI has done some more fine tuned population estimates, which EDS has calculated new estimates.
The changes from the estimates based on projecting Census Bureau estimates are:
FL and TX +1 (to 2 and 4), and NY and MO -1 to (-2 and -1)
Florida had earlier been projected to gain a 2nd seat, and then a slowdown, including net outward migration, had caused the estimate to barely drop below 2. Texas has fluctuated between 3 and 4, and the 4th will be largely dependent on other states, since on a relative share of the USA population it is short of 35.5.
Missouri had been previously been projected to lose a seat, but had more recently been projected to barely hold on.
I suspect that if there was a margin of error attached to the estimates, that the probability of these last switches would be a lot closer to 50% than 100%.
I was at the meeting where these new projections were announced.
ESRI is a major GIS company that provides mapping tools and data sets. One of the
data sets includes current and five-year projections. It's based on Census estimates plus a lot of other data collected by the company and used to adjust the Census estimates. The latest edition was just released, and EDS used the state-level data to calculate apportionments.
Like any estimated data set it's subject to the model used to build it. FL is tricky because of the large number of snowbirds. They can choose either FL or their home state as their Census residence, and its hard to model. I'm told that officials from MN spent time last winter in FL to try to convince those snowbirds from that state to use MN not FL on their Census form. No one knows with any certainty how they finally answered until the figures are released at the end of the year.
