2011 Census: Changing Dissemination Areas

By Dr. Doug Norris, Senior Vice President and Chief Demographer, Environics Analytics

The arrival of boundary files at the lowest levels of geography—dissemination areas and dissemination blocks—means that users will soon be able to visualize updated demographic characteristics at the neighbourhood level. That’s good news for anyone looking to refine a marketing program or analyze changes across locations and over time.

The dissemination area (DA) is the smallest standard geographic area for which all census data are distributed. DAs are composed of a relatively small population, usually between 400 and 700 people. According to the 2006 Census, Canada consisted of 54,626 DAs. In addition, DAs are at the heart of Environics Analytics’ PRIZM segmentation system, with each DA assigned to one of EA’s 66 unique PRIZM segment.

For the 2011 Census, one of Statistics Canada’s objectives was to keep DAs as stable as possible while not allowing DAs to become too large in terms of population. For this reason, and because DAs must respect higher geographic levels—such as census subdivisions (typically municipalities) which may change boundaries—some DAs are modified from one census to the next. According the 2011 Census, there are now 56,204 DAs inCanada, an increase of 1,578 since 2006.

Of the 54,626 DAs identified in 2006, 51,785 (95%) of these geographic units remained the same for 2011. The remainder were modified in various ways. A total of 583 were split into two or more DAs: 313 were split into two DAs and 270 were split into three or more DAs. The biggest split occurred in Milton, Ontario, one of the fastest growing municipalities in the Greater Golden Horseshoe, where one 2006 DA was split into 21 DAs for 2011. An additional 2224 DAs were subject to more complicated changes where parts of one DA were assigned to one 2011 DA and other parts were assigned to others. These were often the result of boundary changes at higher levels of geography. Finally, there were 34 2006 DAs (17 pairs) that were collapsed into 17 DAs for 2011.

Approximately one quarter of the 2006 DAs that were changed in some way are located in small town and rural areas. Many of these shifts were likely the result of municipal boundary changes. Most of the remaining DA changes resulted from increased population in rapidly growing suburbs around large urban areas. One exception was the urban area ofCapeBretonwhere virtually all the DAs were modified in a special redesign of the DA boundaries in order to better match local areas of interest.

We can also look at the DAs that were changed in terms of their 2006 PRIZM segment assignment. Not surprisingly, nearly one quarter of all child-filled Pets and PCs DAs and 17% of Mini Van & Vin Rouge DAs have modified boundaries for 2011. These segments are dominated by new suburban areas with young families. Other segments that had considerable change were New Homesteaders (rural midscale couples and families), Big Sky Families (middle-aged, midscale Prairie farmers), and Grads and Pads (young, lower-middle-class urban singles). When the new version of PRIZM based on the 2011 Census and National Household Survey data is released in early 2014, some DAs might change from one segment to another, reflecting demographic changes in the last five years. In addition, new segments might be introduced and others retired from use.

The 2011 Census counts for the dissemination areas will be released on February 8, 2012. Since 95% of DAs have not changed since 2006, this means that it will be possible to directly compare the 2006 and 2011 populations for most the DAs in Canada.