Why is normalizing data such a big deal?
Changing track boundaries mean that it is difficult to compare track data over time. In the example below, a section of Allen County, IN is shown broken-out at the census tract level. At a glance, one can observe that there are changes in the census tracts from 1980 to 2000. In fact, Allen County, IN has a nice example of tracts merging, splitting, and merging/splitting into new parts. Overall, the number of tracts grew from 82 in 1980 to 90 tracts in 2000, a 10% increase. Subset of Tracts in Allen County, IN in 1980 Boundaries Subset of Tracts in Allen County, IN in 2000 Boundaries Taking a closer look at Allen County from 1980 to 2000 reveals the modifications in tract boundaries that significantly impact how researchers study and account for changes in a population over time. For example, the single 1980 Tract # 011601 broke into two tracts in the 2000 Census (011601 and 011603). It is a straight-forward 1-to-2 correspondence. There are also mergers where two tracts, 002200 and 0024
