Strategies for Analyzing and Using ACS Data

The data available to make your own assessment of the comparability, quality usefulness, and potential benefits of the American Community Survey is initially overwhelming. The data, quality measures, and geography make analysis a challenge. Statistical measures like the differences, standard errors, z-scores and p-values can help to quickly look for significant differences but some statistically significant differences may not be meaningful differences in the world of the data user. In general the ACS appears to be measuring the same things in much the same ways as the census and getting similar results. There is still much to learn about data comparability, reasons for differences and whether "different" is better, worse or just different. There are differences between the Census and the ACS, some statistically significant differences. These may ultimately be welcome differences if the ACS data are consistent, more current and of higher quality than data from the decennial census long-form sample.

Prospects and Predicaments

The American Community Survey has been designed to collect and provide more complete and more current demographic, social, economic and housing information between censuses and to replace the Census 2010 long-form. The success of this endeavor depends upon continuous and adequate funding, sufficient sample sizes, and a current and accurate Master Address File. Shortfalls in any of these areas could reduce data quality. The decennial Census is subject to the same perils.

The ACS faces additional challenges as it continues to evolve and improve:

• Including the population residing in facilities like prisons and dormitories (group quarters).
• Improving the Census Bureau's population estimates that are used as the population controls for the ACS.
• Assisting data users to use series of averaged data and data for small jurisdictions and seasonal areas.

The American Community Survey, in its infancy, can be modified and improved. It is critical that those who use Census data evaluate the ACS survey data and communicate any major issues to the Census Bureau. The result will be more timely, more accurate data for all communities.