Alberta's official health geographies
Alberta Health Services and Alberta Health share one set of standard geographic areas for surveillance, planning, monitoring and reporting. Knowing how those areas nest, how big they are and what each one is for decides whether a rate you report is stable or misleading.
Why the standard exists
When nine geographically based health authorities and three provincial entities were merged into a single provincial organisation, Alberta Health Services, each new AHS zone needed its own set of smaller, contiguous areas for planning and reporting. In 2010 a pan-provincial Geographic Area Working Group, with members from across AHS and Alberta Health, set the principles and methods. Multidisciplinary zone teams then drew the areas inside each zone and validated them with local operations and planning staff.
The guiding idea is that place shapes health through local conditions: history, the built environment, amenities, socio-economic and socio-cultural characteristics, and the services people use day to day. People also tend to seek care where they commute for work.
Ground rules for every area
- Both organisations use the same areas for the same purposes.
- Zones are the largest unit; everything below rolls up into a zone.
- All boundary sets are contiguous, with no gaps or overlaps between levels.
- Rural and urban areas are built with different methods.
- Each level is meant for a particular purpose, and its fit is reviewed over time.
The hierarchy
Five nested levels, all assembled from Statistics Canada dissemination areas. Bars show how many areas each level divides Alberta into.
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Zone
5North, Edmonton, Central, Calgary and South. Formed in 2009 by aggregating the nine former Regional Health Authorities; Redwater moved from Edmonton Zone to North Zone in 2011. Zone boundaries cannot change.
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Subzone
35Built from health status areas to increase sample sizes, especially in rural areas. Populations over 40,000. For high-level reporting and complex rates; mainly used by Statistics Canada, CIHI and Alberta Health.
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Health Status Area (HSA)
64Groups of ALGAs with populations of 35,000 or more. The standard level for population health reporting, and the most appropriate one when common outcomes, utilization or surveillance data need stratifying.
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Aggregated Local Geographic Area (ALGA)
91Groups of LGAs chosen for community likeness, travel patterns and shared services, with populations of 15,000 or more. Suited to common health events with little or no stratification. In Calgary and Edmonton, ALGAs and LGAs are identical because the populations are already large.
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Local Geographic Area (LGA)
132The lowest official level. No target population size, so LGAs range from very small rural areas to large metropolitan ones. For detailed planning, counts, utilization and deep-dive service planning studies.
Dissemination areas are the smallest units for which Statistics Canada releases all census data. They follow municipal boundaries (census subdivisions), are stable from year to year and do not overlap. In the remote north, where DAs are very large, dissemination blocks were used to locate where people actually live.
Choosing a level
Stable estimates for most common health events need a population of about 10,000 to 15,000, sometimes 20,000. The standard sizes areas for common events and moves rarer events up a level.
| What you are reporting | Example from the standard | Level to use |
|---|---|---|
| Individual case management | — | Patient address or postal code; data are not released |
| Common health events | Morbidity | Subzone, HSA, ALGA or LGA, without stratification or by pooling several years |
| Rare health events | Congenital anomalies | Zone |
| Very rare health events | Maternal death | Province |
Rather than shrinking every area to suit rare events, the standard sizes areas for common events and reports rare events at the next level up.
How boundaries were drawn
Across Alberta, areas respect zone boundaries, follow municipal and county boundaries wherever possible, follow natural barriers, line up with Health Advisory Councils where feasible, and take earlier health region boundaries into account.
Rural areas
- Acute care sites stand in for shared services. Catchments were drawn around hospitals using 75–85% of emergency and inpatient utilization.
- Travel patterns, shared infrastructure, local industry and local knowledge of similar populations were also weighed.
- Rivers, lakes, parks, rail lines and major roads were respected, as were municipal boundaries.
- Very large dissemination areas were split according to where people live.
Urban areas
- Built by clustering city-defined neighbourhoods of about 3,000 people; neighbourhoods were never split.
- Existing neighbourhood groups were kept, and common land use (residential, commercial, industrial) was grouped together.
- Housing and population characteristics, shared resources and travel patterns were considered.
- Natural features and transport routes were respected, as in rural areas.
Target sizes: subzones and HSAs 25,000 to 55,000 or more (larger in metropolitan areas), ALGAs 15,000 or more, LGAs no specific target.
The rural–urban continuum
A separate classification built from LGAs for analyses that compare or stratify by rural–urban status. It combines population density, distance to urban and major rural service centres, travel and commuting patterns, and local knowledge.
Metro centres
Populations over 500,000: Calgary and Edmonton proper.
Metro influenced
Commuter communities around the two cities. Calgary: Cochrane, Airdrie, Okotoks, Priddis, Chestermere Lake and the Springbank area. Edmonton: St. Albert, Fort Saskatchewan, Stony Plain and Spruce Grove, Sherwood Park and Leduc.
Urban
Five centres between 25,000 and 500,000: Grande Prairie, Fort McMurray, Red Deer, Lethbridge and Medicine Hat.
Moderate urban influence
LGAs around the five urban centres. Their populations are still too small to separate, so for now they are analysed as rural.
Large rural centres
10,000 to under 25,000 people, defined for special studies: Brooks, Canmore, Wetaskiwin, Camrose, Lloydminster and Cold Lake.
Rural
Under 10,000 people and up to 200 km from a metro or urban centre: towns, villages, hamlets and farmland.
Remote
More than 200 km from a metro or urban centre. Industry is typically oil and gas, forestry, hunting and trapping, tourism and some agriculture.
The 2018 document notes that the urban-influenced categories were under redesign, including demarcating the rural parts of the area around Edmonton.
The 2018 update
The 2010 areas were built from 2006 dissemination areas, with a review planned every five years to follow Statistics Canada boundary changes. By the 2016 Census, Alberta had grown by more than 11% in five years, and towns including Airdrie, Grande Prairie, St. Albert, Spruce Grove, Sylvan Lake, Blackfalds and Red Deer had expanded their boundaries.
The January 2018 update applied 17 boundary changes affecting 29 LGAs, such as Fort McMurray–Wood Buffalo, St. Albert–Sturgeon County West and Airdrie–Crossfield. Area names and codes stayed the same. Zone boundaries could not be changed, and small anomalies from the 2016 census boundaries not lining up with 2006 and 2011 were left as they were.
Planned next steps were a new, finer Sub-Local Geographic Area (SLGA) that rolls up to LGAs, and a rural–urban continuum rebuilt on SLGAs.
What changes, what doesn't
- Changed
- LGA boundaries where city, town or census boundaries moved
- Unchanged
- Names and codes of all areas; zone boundaries
- Reported
- Population impact (2016 dissemination blocks) and postal code changes (June 2017 Postal Code Translator File) for each update
Using them in analysis
Practical habits when working with Alberta health records at these levels.
Say which vintage you used
Because names and codes were kept in 2018 while boundaries moved, the same LGA code can cover a different area in older and newer files. Record the boundary year alongside any area-level result.
Assign by residence, not by facility
Population rates need the patient's home area, usually derived from postal code. The facility a patient attended answers a different question. In Project 001, the regional analysis deliberately groups by the region of the hospital, and keeps patient residence as a separate field.
Match the level to the event
Check counts before mapping. If an outcome is rare, move up to HSA, subzone or zone, or pool several years, rather than publishing unstable small-area rates.
Use the continuum for rural–urban comparisons
The seven categories are designed for stratification, so they are a better choice than an ad hoc urban/rural split, and results stay comparable with AHS reporting.
Expect spatial dependence
The standard cites Tobler's first law of geography: near things are more related than distant things. Neighbouring areas are not independent observations, which matters for models and for cluster detection with tools like SaTScan.
Remember the system has changed
These areas describe the 2018 standard. Alberta's health system has been reorganised since then, so check Open Alberta for the latest boundaries and how current reporting uses them.
Source
Everything on this page is summarised from Alberta Health Services and Alberta Health, Official Standard Geographic Areas, updated January 2018, on Open Alberta. The document includes reference maps, name and code tables and population tables for each level.
The AHS/AH geographic boundaries are in the public domain. Suggested citation: Alberta Health Services and Alberta Health (2017), Official Standard Geographic Areas, Alberta, Canada. This page is an independent educational summary, not an official publication.