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Welcome to episode three of the DRC Online GIS Workshop Series:
Canadian Census Geography.
Episode Objectives: In this video, we will explain how census data is broken down geographically.
We will also talk about choosing an appropriate level a census geography for our project.
Understanding Census Geography. The Canadian census is conducted every five years.
It counts the number of people in Canada and collects a variety a demographic
information about them
including, amongst other things, age, income
education, and family makeup. The census is useful for mapping,
as census data is always tied to a geographic area,
sometimes to within a few city blocks. For example,
we can find out not just the population of Guelph,
but the number of children under twelve who live in a specific neighborhood.
For the purposes of the census, Canada is divided into different geographic areas.
There are several levels of census geographies,
some more specific than others. We see here
a simplified graphical representation of the census geography hierarchy.
Census data is recorded at these and other levels.
We are all familiar with province and territory divisions.
This is the largest and least specific level of census geography.
Here we can see a map Eastern Canada showing the outlines of the provinces and territories.
Note that each province and territory division has a two-digit unique identifier
code. For example, Ontario's unique identifier code is thirty-five.
The provinces and territories are completely divided up into census divisions.
Census divisions often correspond to county boundaries.
Here, we can see a map of Ontario showing the census division boundaries
from the 2011 census.
Note that each census division has a four-digit unique identifier code
made up of the two-digit provincial code
plus a two-digit census division code. For example,
the Wellington census division has a unique identifier
code of 3523.
Each census division is further fully divided into census subdivisions.
Here we can see a map southwestern Ontario
showing census subdivision boundaries in blue.
Census divisions are shown in red.
Census subdivisions often correspond to municipal boundaries.
Census subdivisions always respect census division boundaries.
There can never be a census subdivision that lays half in one
census division
and half in another. Note that each census subdivision has a seven-digit
unique identifier code, made up of the two-digit provincial code,
the two-digit census division code, and the three-digit census subdivision code.
For example, the Guelph census subdivision has a unique identifier
code of 3523008.
Each census subdivision is fully divided into dissemination areas.
Here we can see a map of Guelph showing the dissemination areas in green.
Census subdivisions are shown in blue. Dissemination areas respect census
subdivision boundaries,
There can never be a dissemination area that lays half in one census
subdivision and half in another.
As we can see, dissemination areas are quite small,
especially in urban areas. Note that each dissemination area
has an eight-digit unique identifier code, made up of the
two-digit provincial code,
the two-digit census division code, and a four-digit dissemination area code.
For example the dissemination area in which the University of Guelph
is located has a unique identifier code of 35 23 0187.
Census metropolitan areas and census agglomerations only exists for areas
consisting of one or more neighboring municipalities situated around a core.
Census metropolitan areas must have a total population of at least one hundred thousand,
of which fifty thousand must live in the core.
A census agglomeration must have a core population of at least ten thousand.
Here we can see a map of southwestern Ontario
showing census metropolitan areas in brown and census agglomerations in grey.
Census metropolitan areas and census agglomerations are typically presented
together in the same map.
Note that each census metropolitan area and census agglomeration
has a three-digit unique identifier code. For example,
the Guelph census metropolitan area's unique identifier code is 550.
Census tracts only exist within census metropolitan areas and census
agglomerations that have a core population of fifty thousand or more.
Here we can see a map of Guelph showing census tracts in purple.
Note that each census tract has a ten-digit unique identifier
code, made up of the three-digit census metropolitan area code,
and a seven-digit census tract code. The seven digits include a decimal point.
For example, the census tracts in which the University of Guelph is located has a
unique identifier code of 55 0000 1.03.
Province, census division, census subdivision,
census metropolitan area, census agglomeration
census tract and dissemination area. These are the most commonly used levels of
census geography. There are even more levels available,
but we won't go into them here. Visit the links to the Statistics Canada
website that accompany this video
to learn more about the different levels census geography.
Choosing an appropriate level of census geography requires that we consider both
our project requirements, and the available data.
First, let's talk about project requirements. Think about the level of
detail we need to complete our project.
For example, a project comparing the population of one city to another
may only need data at the census metropolitan area level.
Here we can see a map showing all Ontario census metropolitan areas
and census agglomerations by population.
This map shows that census metropolitan areas and census agglomerations located
southern Ontario tend to have higher populations than those located in northern Ontario.
Another project that aims to compare the demographics of different parts of the same city
may need data at the dissemination area level. Here we can see a map of Guelph
showing dissemination areas by the number of people aged 65 and older.
We can see that the distribution of seniors across Guelph
varies greatly. Perhaps this encircled dissemination area
with a high number of seniors, located in west central
Guelph, would be a good place to locate seniors' center.
Second, let's talk about the availability of data.
Not all census data is available for all levels the census geography.
The smaller and more specific the level a census geography,
the less data will be available. To find out what data is available for which
levels census geography,
we can visit the Statistics Canada website or
we can visit Odesi, a data portal, that is available to Ontario University students.
We will use Odesi in a future video. For this video,
let's use this Statistics Canada website to determine data availability.
From the Statistics Canada home page, click on Census of Canada,
then click on Data Products.
Choose topic-based tabulations. Notice that there are several topics for which
census data is available,
such as age and sex, families, households and marital status,
structural type of dwelling and collectives, and language.
Click on Age and Sex. All of the available tables containing
age and sex data for different levels census geography
are available from this page. Now, let's think about our school siting project.
We want to know the distribution of children aged twelve and under across Guelph.
It's important that our understanding of this distribution be as
detailed as possible
because we want to be able to determine the best placement for our school.
Therefore, we want to use the smallest and most specific level of census
geography for which
age data is available. Upon reviewing this page,
we can see that the most detailed level of census geography for which
age data is available is dissemination areas. Don't download this table -
for now it's enough to know that this is the appropriate level of census geography
for our project.
In order to display census data on the map, we need two datasets:
a polygon vector file showing the boundaries of the level of census
geography we have chosen,
and the table containing the census data we wish to display,
reported at the same level of census geography as the boundary file.
These two datasets can be joined together
based on the unique identifier code to display the data on the map.
This process will be described fully in a future video.
In this video, we talked about how census data is broken down geographically.
We also chose an appropriate level of census geography for our project.
Do you have questions about the content of this video? Staff in the Data Resource Centre
are ready to assist you.
Drop-ins and appointments are welcome. Please check the DRC's website for our hours.
You can also email us at drchelp@uoguelph.ca.
Thanks for watching!