Health Inequities in Manitoba: Is the Socioeconomic Gap

Health Inequities in Manitoba: Is the Socioeconomic Gap in Health Widening or Narrowing Over Time?
Chapter 2: A Description of the Neighbourhood Income
Quintiles using Census Data
This report analyses various health and social indicators over time by using neighbourhood income
quintiles as a proxy for socioeconomic status. Neighbourhood income quintiles divide the Manitoba
population into five neighbourhood income groups (from lowest neighbourhood income to highest
neighbourhood income) so that approximately 20% of the population is in each group. They are
created within two population groups: urban (Winnipeg and Brandon) and rural (other Manitoba areas).
The indicator analyses in Chapters 3 through 8 use the Data Repository housed at MCHP, in which
individuals are assigned an neighbourhood income quintile based upon their postal code via the Postal
Code Conversion File (PCCF). The PCCF is provided by Statistics Canada and links postal codes to Census
Dissemination Areas (DA). In the Census, DAs are the smallest geographical areas available for which
all census data are disseminated. (Census Divisions and Sub–divisions are larger geographical areas
available in the Census.) DAs usually contain between 400–700 people and are approximately the size of
one city block in urban centres. In this chapter, we wish to explore census data indicators not available
in Repository such as the percent of the population who are of aboriginal origin or the percent who are
immigrants. However, we cannot simply work backwards to map DAs onto their corresponding postal
codes to assign neighbourhood income quintiles to DAs because DAs can cover more or less area than
postal codes within the same geographical space, and overlapping can occur. As such, this chapter has
used a slightly different methodology to assign neighbourhood income quintiles to geographical areas.
Tables and graphs in this chapter characterize information from the 1986, 1996, and 2006 census
by neighbourhood income quintile. Dissemination areas (formally enumeration areas prior to 2001)
are assigned to a neighbourhood income quintile based on the average household income cut–offs
developed by MCHP during creation of the quintiles. Each neighbourhood income quintile based on
the Manitoba population, U1 through to U5 and R1 through to R5, have corresponding minimum and
maximum average household income values. To classify DAs to one of the neighbourhood income
quintiles, each DA was first determined to be either urban (Winnipeg and Brandon) or rural; and then
the DA was sorted into one of the quintiles based on where the average household income of that
DA lay within the cut–offs. For DAs with missing or suppressed income, imputation for an average
household income was attempted. Where possible, the Census Sub–Division’s (CSD) average household
income was used to approximate the DA’s average household income. However, DAs associated to
First Nation communities often have a missing average household income at both the DA and CSD
level. Therefore, a different imputation was done; the mean household income for the North and South
First Nation communities were calculated and then assigned to each North and South First Nation DA
respectively. After these two rounds of imputations, any remaining DAs with missing or suppressed
income were placed into the not found (NF) income group. Despite being counter–intuitive, this
method produced the best possible estimates for classifying DAs into neighbourhood income quintiles
given the limitations with applying MCHP Data Repository methods to the census data. Once all DAs
were converted into rural and urban neighbourhood income quintiles, a weighted percentage was
calculated for each of the census characteristics by neighbourhood income quintile.
There are several limitations to this chapter’s information. According to the census, Manitoba’s
population is approximately 3% smaller than is found in the Repository at MCHP, which could lead to
slightly different percent of the population in each neighbourhood income quintile. The 2006 census
contained 2,152 DAs for Manitoba. Thirty–seven DAs had an average household income that was
Manitoba Centre for Health Policy 15