The Census Bureau’s American Community Survey (ACS) is an ongoing survey that provides data every year about things like income, education, veteran status, and transportation. For more information, please visit the Census Bureau’s ACS webpage.
The ACS reports its data in a format different from that of the 2000 Census. While the data for the ACS are collected every year, only about one in every 38 households are surveyed per year. In order to calculate more accurate estimates, the Census has scheduled the ACS releases into three sets: 1-year, 3-year, and 5-year. Data are released for each set every year, but the sets all cover different levels of geography. The 1-year data are available only for states, some counties, and cities with populations of at least 65,000 people. The 3-year data contains data collected and averaged over a 3-year period for states, most counties, and cities with populations of at least 20,000 people. The 5-year data contains data collected and averaged over a 5-year period for all geographic areas down to the Census block group.
MVRPC has chosen to put together an ACS Regional Profile using the 5-year data because it is the only data set that contains information for all of the jurisdictions in our Region.
The Regional Profile is broken into two parts. The first is a set of Regional Profile packets we are releasing for the Regional Planning Commission area, a larger eight-county region, and individually for the eight counties. These packets contain a set of maps and charts that present selected data from the ACS. The second part is a spreadsheet, available both in Excel and PDF formats, which contain selected ACS data broken down by county, township, and municipality.
Before you download the data, however, a word of caution. The samples from which this data were drawn, especially in the smaller geographic areas and more rural areas, can be very small. This makes the estimates more unreliable. The Census provides a margin of error along with the estimates both to give you a better idea of how reliable the estimates are and to allow you to perform comparisons using the data between geographic areas and across time (as a general rule of thumb, the larger the margin of error, the less reliable the data).
However, this means that simple comparisons are no longer possible. In order to compare two areas or data from the same area for two different time periods, you will need to conduct a significance test. This page from the Census will tell you what data is able to be compared across time, and this handbook for general data users contains more information and detailed instructions for performing comparisons. As always, please contact us if you have any problems or questions about working with this data.
When you download the ACS Regional Profile packets, you will notice that the maps look different. They are no longer simple maps showing the ranges for a particular data point for different geographic areas in the Region. Instead, we have had to compare the estimates for each of the Region’s Census tracts to a larger area. For the regional maps, this larger area is the Region as presented. For the county maps, the county serves as the larger area. The tracts are then divided into three groups: significantly higher than the larger area, not statistically different from the larger area, or significantly lower than the larger area. We realize that this kind of presentation may not be optimal, but it is the best way to present this kind of data. Again, please feel free to contact Elizabeth Whitaker, Research Associate with any questions about using or interpreting this data.
Download some tips for using ACS information.