Question
I have a student who is working with census tract data from Calgary for a geography assignment. He’s looking for a conversion table that he can use to match up the tracts from 1996 until 2006, which have changed. Do you have any suggestions on where he could find this?
Answer
Try the correspondence files :
http://www5.statcan.gc.ca/bsolc/olc-cel/olc-cel?lang=eng&catno=92-156-X
but working with census tracts should be easy to trace back – from the Illustrated Glossary
http://www.statcan.gc.ca/pub/92-195-x/2011001/geo/ct-sr/def-eng.htm
Changes to census tract boundaries are discouraged in order to maintain maximum data comparability between censuses. Boundary revisions rarely occur, and only when essential. Road construction, railroad abandonment, community redevelopment, neighbourhood growth and municipal annexations may contribute to changes in census tract boundaries. A census tract may be split into two or more new census tracts (usually when its population exceeds 8,000). CT splits are usually done in a way that allows users to re-aggregate the splits to the original census tract for historical comparison. Census tract naming is consistent from census to census to facilitate historical comparability. When a CA enters the census tract program, the census subdivision (CSD) that gives the CA its name is assigned the first CT 'name,' starting at 0001.00. When all of the CTs within the first CSD are named, then the CTs of the adjoining CSDs are named, and finally those on the periphery are named. If a census tract is split into two or more parts due to a population increase, the number after the decimal point identifies the splits. For example, CT 0042.00 becomes CT 0042.01 and CT 0042.02. If CT 0042.01 is subsequently split, it becomes CT 0042.03 and CT 0042.04. Similarly, if CT 0042.02 is split after CT 0042.01, it becomes CT 0042.05 and CT 0042.06. Any splits occurring after this would be numbered in a similar fashion, with the next sequential number. This allows users to re-aggregate the splits to the original census tract.
