2000115-Strengthening-Communities-with-Neighborhood-Data

82 Strengthening Communities with Neighborhood Data
Program (US Department of Housing and Urban Development 2010b,
n.d.b). These data represent an important precedent in transforming
commercially valuable data to a less-detailed form in the public interest.
These data are also significant for their timeliness and frequency. HUD
publishes the data quarterly and with less than two months’ lag, vastly
improving their value to policymakers and housing practitioners. The
data still exhibit some of the downsides of proprietary data. For example,
there is no documentation on changes in methodology that cause swings
in indicator values, nor is there a way for researchers to submit inquiries
to the producers of the data. 1
In December 2010, the United States entered a new data era when the US
Census Bureau released the first set of five-year American Community Survey
(ACS) data. The Census Bureau designed the ACS to replace the former
long form of the Decennial Census and increase the frequency of updated
data. ACS provides annual releases of data so that users don’t have to wait
10 years for a Decennial Census update. 2 The Bureau releases one-year data
for geographic areas with a population of 65,000 and higher; three-year
data for areas with a population of 20,000 and higher; and five-year data
for all areas, including block groups and census tracts. Because the ACS is
now administered every month, the Bureau can maintain a consistent level
of operations compared with the drastic ramp-up previously needed for
the long form. This change means that the Bureau can maintain a set of
long-term, trained staff to execute the survey, resulting in improved data
collection practices.
Users of all technical abilities are struggling to learn how to responsibly
analyze, interpret, and communicate indicators based on the fiveyear
ACS data. The obvious change is that the five-year ACS data are
a period estimate, reflecting conditions over the entire time period, in
contrast to the point-in-time estimate in the long-form. This difference
would be difficult to communicate to a lay audience at any time, but
the problem was compounded by the timing of the inaugural five-year
estimates. The years 2005 to 2009 straddled the end of a boom period
and the start of the housing crash and Great Recession, so indicators on
economic conditions and housing values did not match with the general
understanding of conditions at the time of the data release.
Users faced another learning curve in the need to consider margins
of error. Margins of error existed for all long-form Decennial Censuses,
but the Census Bureau did not publish them or emphasize their use.
The lower sampling rate in the ACS results in higher margins of error