I have a student asking the following question."When comparing census data from, say, the
Census of Population over multiple censuses (say 1981-2011) is there a sort of concordance table for the actual data to allow for longitudinal analysis? For example, in 1981 there are less data types than in 2011, and I would like to figure out which ones are similar and/or can be compared over the period?" Any help with this would be appreciated.
Answer
If by longitudinal analysis they mean following the same people over time, I think that the short answer is no (unless you work for Statistics Canada, and even then with some considerable difficulty of matching individuals).
If that's not what's meant by longitudinal analysis, the Census Dictionary <http://www12.statcan.gc.ca/census-recensement/2011/ref/dict/98-301-X2011001-eng.pdf> for 2011 gives the detailed history of how a variable was defined.
Example: CENSUS FARM
A farm, ranch or other agricultural operation producing agricultural products for sale. Also includes: feedlots, greenhouses, mushroom houses and nurseries; farms producing Christmas trees, fur, game, sod, maple syrup or fruit and berries; beekeeping and poultry hatchery operations; operations with alternative livestock (bison, deer, elk, llamas, alpacas, wild boars, etc.) or alternative poultry (ostriches, emus, etc.), when the animal or derived products are intended for sale; backyard gardens if agricultural products are intended for sale; operations involved in boarding horses, riding stables and stables for housing and/or training horses even if no agriculture products are sold. Sales in the previous 12 months are not required, but there must be the intention to sell.
Note: For the Yukon, Nunavut and Northwest Territories only, the definition also includes operations involved in the following:
• herding wild animals (such as caribou and muskox)
• breeding sled dogs
• horse outfitting and rigging
• harvesting indigenous plants and berries.
Notes:
1. For the 1981 and 1986 censuses, a census farm was defined as a farm, ranch or other agricultural holding with sales of agricultural products of $250 or more during the previous 12 months. Agricultural holdings with anticipated sales of $250 or more were also included.
2. For the 1976 Census, a census farm was defined as a farm, ranch or other agricultural holding of one acre or more with sales of agricultural products of $1,200 or more during the year 1975. The basic unit for which a questionnaire was collected was termed ‘agricultural holding’. This term was defined as a farm, ranch or other agricultural holding of one acre or more with sales of agricultural products of $50 or more during the 12-month period prior to the Census Day.
3. Prior to the 1976 Census, a census farm was defined as a farm, ranch or other agricultural holding of one acre or more with sales of agricultural products of $50 or more during the 12-month period prior to the Census Day.)
However, comparing any census to 2011 is somewhat fraught. Unless they want to look only at the 2011 Census variables (age/sex/language/household relationships/etc.), most of the data disappeared into the NHS, and Statistics Canada warns in various guides/reference material against its comparability with Censuses (especially for small area data).
The period from Confederation to 2001 can be tracked using the 2001 Census Handbook,the relevant table begins on page 29: <http://www12.statcan.gc.ca/access_acces/archive.action-eng.cfm?/english/census01/Products/Reference/2001handbook/pdf/92-379-XIE02001.pdf>
2011 is fairly easy to map to this, though 2006 would take longer. Perhaps a similar table was made for 2006 but I can't find one. There is this appendix from the 2011 Census Dictionary which details which variables were available from Confederation until 2011: Appendix A: Census questionnaire content and derived variables since Confederation
<http://www12.statcan.gc.ca/census-recensement/2011/ref/dict/app-ann001-eng.cfm>.
Along with the sources already mentioned, there is the "Census PUMFs
Variable Guide":
Walter Giesbrecht, Alia Ahmad, Elaine Grisola, Joshua Mildenberger and Nazia Sheikh, "Replication data for: Census PUMFs Variable Guide", <http://hdl.handle.net/10864/10540> V2 [Version]
Click on the 'Data & Analysis' tab to get the Excel file and explanatory PDF. It lists all the variables appearing in individual census PUMFs from 1971-2006 (2011 is yet to be added). You can easily see what variables are available in what census years, with the variable names listed for easy look-up in the code books.
Something that also matters is the geography they are examining. Cities and CMAs have changed quite a bit overtime, as have the geographies of eas, das, cts and so on. Boundaries shift, amalgamation occurred from the mid 1990s onward on many cities in Canada. Therefore, not only have concepts changed, but so too have the underlying geographies. if they are looking at any geography below the level of the province then they will have to look at maps.
