Comparing 2005-2009 ACS 5-year estimates and Census 2000 Estimates
Data users need to be aware of differences between the American Community Survey and Census 2000 that will impact comparability of the 2005-2009 ACS estimates and Census 2000 estimates. There are differences in the universe,question wording,residence rules,reference periods, and the way in which the data are tabulated.
The strength of the ACS is in estimating characteristic distributions. We recommend users compare derived measures such as percents,means,medians, and rates rather than estimates of population totals.
In general, these characteristics are comparable. Cases where differences in question wording (Q), reference periods (RP), tabulation (T), and universes (U) may impact comparisons are noted in parentheses. Specific item-by-item guidance is also available.
The 2010 Census will be the benchmark for these characteristics. If your
analysis does not involve other ACS characteristics, you should use the
2010 Census to compare the distributions back to Census 2000.
In general, Census Bureau analysts have determined that differences
between ACS and Census 2000 prohibit an appropriate comparison between
the two. While it may be possible for some analyses, the Census Bureau
recommends extreme caution.