On this page some of the technical components of the project are discussed, such as: the source of the spatial data and how we transformed it, the sources for the attribute data and how we transformed and classified it, and choices made with respect to the reporting periods used in our analyses.

The base maps used in producing the maps presented in the Immigration and Greater Vancouver Atlas were obtained from Statistics Canada under the Data Liberation Initiative.  Using Arc/Info we imported the digital cartographic files and extracted only those Census Tracts which fell within the CMA of Vancouver.  We then projected the data from Geographic coordinates (longitudes and latitudes) to UTM coordinates.  It was necessary to project the data since, at Vancouver's latitude, a degree of longitude is approximately 65% that of a degree of latitude, and a map produced using longitudes and latitudes (e.g., a Platte Carre map) appears severely distorted.  The UTM projection is the most commonly used projection in Canada and, while it is a conformal projection, the amount of areal distortion is minimal when examining a region as small as the Vancouver CMA.

The attribute values (i.e., the census data) were also obtained from Statistics Canada under the Data Liberation Initiative, and through the Metropolis Project itself.  For details on the attribute data, refer to the Discussion and the Definitions pages.  In producing the maps Census Tract (CT) data was used rather than Enumeration Area (EA) data for several reasons, including graphic constraints (using EAs would make the online maps far too busy, and most of the detail would not be decipherable anyway), confidentiality issues and data suppression by Statistics Canada.

We mapped the attribute data using location quotients (LQ).  They are a widely used index which summarizes how concentrated, or not, a group or activity is within an area.  The location quotient for a specific group i in an area is the ratio of the percentage of the total population in group i in the CT under consideration to the percentage of the total population (of the CMA) who belong to group i.  Location quotients above 1 indicate that you are more likely to find members of a group in the CT than you would expect on average, whereas values below 1 indicate that you are less likely to find members of a group in the CT than you would expect on average.  For example, if the percentage of people born in Hong Kong is 4.8% for the entire CMA, then a census track which has 9.6% of its inhabitants born in Hong Kong will have an LQ of 2.0 while a census track with only 2.4% of its inhabitants born in Hong Kong will have an LQ of 0.5. The LQ is a dimensionless index, so the LQ values are directly comparable across the 21 maps.

The legend categories were selected in order to highlight those census tracts that are either above or below the CMA average .  The central division was designed to straddle the expected value of 1.0 (+- 0.15).  The adjacent classes used fixed spans unless the data itself has a smaller range, in which case the upper or lower class limits were set explicitly to the data value.  Census tracks colored white are either tracts for which no data exists , or tracts in which no members of the highlighted group are found .

Throughout the Atlas we have used standard Statistics Canada census reporting periods (e.g., 1981, 1986, 1991 and 1996) and classification schemes.  If you have any questions concerning the definition of a variable, please refer to our Definitions page first.  If you can't find what you are looking for there, please look at the information Statistics Canada provides--links to the most relevant pages can be found at UBC's Data Library Census of Canada Documentation pages (If any questions still remain, please contact us.)