Census Estimates for 2009 -> 2010 Apportionment

[muon2]

The Census Bureau released its new estimates for the population of the states as of July 1, 2009. As in past years I have used that data to project the April 1, 2010 apportionment populations. This requires finding the population growth in the resident population for each state, then applying that to the apportionment population. In this method I assume that the growth until April 1, 2010 will match the uniform growth from April 1, 2000 to July 1, 2009.

One special circumstance is to account for the effect of hurricane Katrina. LA saw an estimated drop of 250 K in the 10 months following the hurricane. If I used the normal methodology, that would project a continued decline through 2010. Instead, for LA I took the percentage growth from July 1, 2006 to July 1, 2009 then applied that to the estimate for July 1, 2006 to get April 1, 2000. To this I added the difference between the resident and apportionment populations in 2000 to reach a projected apportionment population for 2010.

Based on this projection, the following adjustments would be required to reapportion the seats in 2010:

AZ +2
FL +1
GA +1
IL -1
IA -1
LA -1
MA -1
MI -1
MN -1
NV +1
NJ -1
NY -1
OH -2
PA -1
SC +1
TX +3
UT +1
WA +1

Compared to last year's projection this is a shift of two seats from FL and TX to MO and WA. The last states awarded seats were NY 28 (431), WA 11 (432), AZ 10 (433), MO 11 (434) and CA 53 (435). These seats are on the bubble and most at risk to fluctuations in growth during the time from the estimate last summer until Census Day. The effects the the recession damping growth in states like AZ are particularly important. I'll post an alternate analysis to look at that effect later in this thread.

The next five seats would go to FL 27 (436), TX 36 (437), MN 8 (438), OR 6 (439), and NC 14 (440). These are the bubble states on the other side, and can benefit from fluctuations in their favor.

[muon2]

The recession has fallen late in the decade, and it has had a particularly hard impact on housing and relocation. Many states that had seen robust growth for most of the decade have seen that growth slow down substantially. I have made a simple model for the effect of the recession on projections for apportionment. These can be compared to my decade-long baseline noted at the top of the thread.

For this model I have taken the estimated populations for July 1, 2007 and July 1, 2009 as released today and used that two-year period to calculate an annual rate of growth. I then applied that rate for 3/4 of a year on the July 1, 2009 data to get a base projection. To account for military and other overseas residents counted for apportionment I added the difference from 2000 to the 2010 projection.

Based on this projection, the following adjustments would be required to reapportion the seats in 2010:

AZ +1
FL +1
GA +1
IL -1
IA -1
LA -1
MA -1
MI -1
MN -1
NV +1
NJ -1
NY -1
OH -2
PA -1
SC +1
TX +4
UT +1
WA +1

Compared to my conventional model, this projection shifts a seat from AZ to TX. In this model the last states awarded seats were NY 28 (431), WA 11 (432), CA 53 (433), MO 11 (434) and TX 36 (435). The next five seats would go to MN 8 (436), OR 6 (437), AZ 10 (438), NC 14 (439), and FL 27 (440). They are actually fairly close in their outcomes with the same states on the bubble under both models.

[muon2]

What type of growth would NC have to see to gain an EV?

Depending on the growth model for the other states, NC would need between 40 K to 60 K more than is currently projected.

[muon2]

Here's the map from my first set of projections in Atlas form. Feel free to use it for discussions about 2012, 2016 or 2020.

[muon2]

My projection:

• +4: Texas
• +1: Arizona, Florida, Georgia, Nevada, South Carolina, Utah, Washington
• -1: Illinois, Iowa, Louisiana, Massachusetts, Michigan, Minnesota, New Jersey, New York, Pennsylvania
• -2: Ohio

My Excel spreadsheet (Google Docs)

Your spreadsheet doesn't show the formulas for your 2010 estimates. It looks like you are only using the 2008-2009 rate, but even then I can't get the same value that you do. Are you using future value formulas to get the exponential growth for the 3/4 of a year that remain from 7/1/09 to 4/1/10?

The last seat is quite sensitive to the rate you apply, particularly for AZ. The single year rates fluctuate a lot for the states, even for years before the recession. The recession knocked the estimated rate in AZ from 2.7% to 2.2% to 1.5% over the last three years. The estimates had TX fairly close to 2.0% all three of those years. If AZ picks up to a rate like 2.5% for the final nine months as housing starts to pick up, then it passes TX to gain the seat that MN is losing. If MN regains its 0.8% rate from 2007 for the last nine months then MN keeps the seat instead.

[muon2]

My Excel spreadsheet (Google Docs)

Your spreadsheet doesn't show the formulas for your 2010 estimates.

Ah, OK...go to the VIEW menu and check "Show formula bar"

Thanks, that helps. You have a fairly complicated way to estimate the rate for the missing 12 months. In your spreadsheet those 12 months would be the 3 months of the decade from 4/1/2000 to 6/30/2000 and the last 9 months of the decade from 7/1/2009 to 4/1/2010. Your function gives only 1/256 of the weight to the actual rate from 2000-2001 yet gives 3/4 of the rate to the last two years which makes some sense. I would note that gives Texas an unusual boost due to the high rate from the year of Katrina immigration (05-06), which really has no effect in the first or last year of the decade.

I use a simple interest rate calculation. The rate between an estimate and the base value is (est/base)^(1/years)-1. The years can be a fraction such as 9.25 representing the time from 4/2000 to 7/2009. This what I use for my "traditional" analysis, with some adjustments in the Gulf states for Katrina. My alternative analysis uses the rate formula with the 2007 estimate as base and 2 years for the time.

To get the 2010 projection I use a compound interest function est2009*(1+rate)^0.75, which covers the 9 months from the final estimate to the present. I do adjust for overseas population that will be used in apportionment, though that only changes priority this year, not the seats assigned.

[muon2]

The problem with any formula is that it presumes pretty much a continuation of the recent past.

Consider the case of Louisiana, whose population radically decreased as a result of a hurricane.

What if California has a series of major earthquakes in January of 2010?

I completely agree. That's why I try to factor out Katrina from the Gulf and look at the recession years carefully. There's no question that there may be unforeseen events or trends that have been missed. At this point we are almost 10 years since the last complete count and errors will creep in. A formula only provides a rational way of making a projection in the face of incomplete information.

[muon2]

How close is RI to losing its second seat and MT and DE to gaining one?

By my projections RI has only about 30 K people to spare this decade. Their growth rate is near 0, so it seems very likely that they will lose a seat in 2020.

MT is only 30 K short of a seat, but their growth rate is slightly less than the national average. Until their rate gets over the average for a while, they are going to stay just a little short of  a second seat.

DE is about 110 K short of a second seat, so it isn't possible this decade. However, they are growing faster than the national average, and if that continues they could pick up a seat in 2020 or 2030.

[muon2]

So Oregon is not gaining a seat anymore and instead Washington will ? Weird.

And glad to see Texas will gain only 3 !

WA and OR are both close to the line, but the projections right now favor WA. Similarly, TX and AZ may be fighting for the last seat. I have it going to AZ right now, but many other projections give it to TX. That would give them +4.