Tuesday, December 20, 2005

More on the ACS

As I mentioned back in July, the American Community Survey is now the new source of Census data.

Go to the Data Sets section of the Census page. Click on any of the tabs to the right (data profiles, detailed tables, e.g.) Pull down the counties of New York. You'll only find 15 of the 62 counties for the state: Albany, Dutchess, Erie, Monroe, Onondaga, Orange, Rockland, Westchester, plus the counties of New York City and Long Island. Why is that? Because this is data based on sampling, and only the locations that have 250,000 people have data that are "statistically significant" in this round. You'll also notice that the data are presented differently than you may be used to, with a lower bound and an upper bound. In fact, these parameters have been calculated before, but not shown.

Next year, the threshold will be 65,000, as the Bureau expands the process. The places with 20,000 to 65,000 people will be calculated based on a rolling three-year average, so there will be no data until 2008, but will come out annually therafter. Smaller places will be generated using a rolling five-year average, with data coming out each year starting in 2010. The 2010 Decennial Census should be a short form for everyone. Naturally, this depends on Congressional funding, which is secure for the 2006 budget.

Another aspect of ACS that is different from the traditional Census rules is the residency rules. While the decennial census asks for one's "usual place of residence," i.e., your primary home, the ACS asks for current residency. Since the survey is conducted year-round, the Census Bureau will get a better handle on seasonal and migratory populations.

Of course, since the forms are sent to each address, it is important to know what those addresses are. Census regularly does a Boundary and Annexation Survey, reflecting address changes. This could be streets changing names or numbering, demolition, new construction or border changes. Read more about this here.

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