A Migration Mystery
As I recently tooled around the San Diego Chamber of Commerce website, I came across a document called the "San Diego Economic Bulletin: Forecast 2005 & 2006." This document is a gold mine of the kind of local data that causes a nerd like me to mewl with delight.
But my delighted mewling turned to confused mewling as I read the section on population growth.
The first accompanying chart indicates the U.S. Census Bureau's take on who's coming and going in San Diego. (Readers who are particularly interested or lonely can find the gigantic Census Bureau spreadsheet here.)
According to the Census folks, our population growth has been steadily decreasing and actually went slightly negative in 2005. More striking, though, was the trend in net migration, which removes the effects of births and deaths to directly measure how many people are moving into, or out of, San Diego. Per Census measurements, San Diego has experienced a growing trend in net out-migration since 2003.
The Chamber of Commerce report, on the other hand, indicates a healthy and somewhat steady increases in both population and net migration. The Chamber's figures are shown in the second chart, which uses the same scaling as the first chart so a direct visual comparison can be made.
As you can see, the difference is quite striking.
Hence my confusion. What could account for such a disparity?
The Census time periods start and end in the middle of the calendar year. Maybe the Chamber uses a calendar year timeframe, but there is no way that this could account for such a huge difference in the numbers.
Perhaps Chamber and the Census Bureau are including different areas in their definitions of what comprises "San Diego." This theory is supported somewhat by the fact that the organizations have different estimates for overall population. Whereas the Census counted 2,933,462 San Diegans in 2005, the Chamber counted 3,078,383--a difference of 144,921 people. However, both organizations claim that their numbers are for "San Diego County," the definition of which seems like it should be pretty clear.
I wrote to the Chamber in an attempt to find out what might account for such a conflict between the two reports. I was informed that the person who compiled the data for the last report was no longer employed at the Chamber, that this year's updated report is soon to be published, and that they'd "take a look at the previous briefing and see how to best proceed."
I appreciated the promptness of their response, even if the content wasn't terribly decisive.
This is pretty important stuff. It is surely more difficult for San Diego businesses -- housing, retail, services, or otherwise -- to plan properly if they don't even know whether their potential customer base is shrinking or growing.
I will try to figure out what's going on and report back accordingly. Meanwhile, the report is still up on the Chamber of Commerce site, so I guess they aren't too worried about it.
-- RICH TOSCANO
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