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2A Income Inequality


Description | Specific Indicators | Corresponding Mandatory Objectives | Corresponding National Indicators | Data Sources | Survey Questions | Alternative Data Sources | Analysis Check List | Method of Calculation | Basic Categories | Indicator Comments | Definitions | Cross-References to Other Sections | References


Median share of income is the proportion of income (from all sources, pre-tax, post-transfer) held by all households whose incomes fall below the median household income.  A proportion of 50% would represent zero inequality.  A proportion of 0% would represent complete inequality. Note:  There is no one single measure of low income or income inequality. When looking at low income, the median or average income or household income in respective time periods or regions can be used.  Median household income is the dollar amount that marks the midpoint of a distribution of households ranked by the size of household income.

Specific Indicators

Median share of income

Ontario Public Health Standards (OPHS)

The Ontario Public Health Standards (OPHS) establish requirements for the fundamental public health programs and services carried out by boards of health, which include assessment and surveillance, health promotion and policy development, disease and injury prevention, and health protection. The OPHS consist of one Foundational Standard and 13 Program Standards that articulate broad societal goals that result from the activities undertaken by boards of health and many others, including community partners, non-governmental organizations, and governmental bodies. These results have been expressed in terms of two levels of outcomes: societal outcomes and board of health outcomes. Societal outcomes entail changes in health status, organizations, systems, norms, policies, environments, and practices and result from the work of many sectors of society, including boards of health, for the improvement of the overall health of the population. Board of health outcomes are the results of endeavours by boards of health and often focus on changes in awareness, knowledge, attitudes, skills, practices, environments, and policies. Boards of health are accountable for these outcomes. The standards also outline the requirements that boards of health must implement to achieve the stated results.

Outcomes Related to this Indicator
  • Societal Outcome (Foundational Standard):  Population health needs are anticipated, identified, addressed, and evaluated.

 Assessment and/or Surveillance Requirements Related to this Indicator

  • The board of health shall assess current health status, health behaviours, preventive health practices, health care utilization relevant to public health, and demographic indicators in accordance with the Population Health Assessment and Surveillance Protocol, 2008 (or as current) (Foundational Standard)
  • The board of health shall conduct surveillance, including the ongoing collection, collation, analysis, and periodic reporting of population health indicators, as required by the Health Protection and Promotion Act and in accordance with the Population Health Assessment and Surveillance Protocol, 2008 (or as current) (Foundational Standard).

 Protocol Requirements Related to this Indicator

  • The board of health shall collect or access the following types of population health data and information: Socio-demographics including population counts… (Population Health Assessment and Surveillance Protocol, Data Access, collection and management, 1b)

Corresponding Health Indicator(s) from Statistics Canada and CIHI

The internet publication Health Indicators, produced jointly by Statistics Canada and the Canadian Institute for Health Information, provides over 80 indicators measuring the health of the Canadian population and the effectiveness of the health care system. Designed to provide comparable information at the health region and provincial/territorial levels, these data are produced from a wide range of the most recently available sources.  A pdf copy of the Health Indicators e-publication report can be found on CIHI’s website ( at

Corresponding Mandatory Objectives

  • None

Corresponding National Indicators

Data Sources (see Resources: Data Sources)
Numerator & Denominator:
Canadian Census, National Household Survey
Original source:
Statistics Canada
Distributed by:
Statistics Canada, Health Indicators

Suggested citation (see Data Citation Notes):
[year] Census (special tabulations), Statistics Canada, National Household Survey
[year] National Household Survey, Statistics Canada

Analysis Check List


Method of Calculation

The health-region (HR) specific median household income is determined. The incomes of the bottom half of all households in that HR are summed, as are the incomes of the top half of all households in that HR. The total household income of the bottom half of households is divided by the total household income of all households in the health region. This represents the "proportion of income held by households whose incomes fall below the median household income."

TIBM: Total income of all households below the median income
TIA: Totall income of all households

Median Share of Income = TIBM / TIA x 100 (expressed as a %)

Example A: Median income of Health Region (HR) A is $20,000. The total income of the half of households in HR A whose incomes fall below the median is $1,000,000. The income of the households in this HR whose incomes are above the median is $4,000,000. Thus, the proportion of income held by the bottom half of households in HR A, that is, the median share of income, is (1,000,000/5,000,000) = 20%.

Example B: The median household income within HR B is also $20,000. The total income of the half of households in HR B whose incomes fall below the median is $1,000,000. The income of the households in this HR whose incomes are above the median is $6,000,000. Thus, the proportion of income held by the bottom half of households in this HR, that is, the median share of income, is (1,000,000/7,000,000) = 14%.

These examples demonstrate that two HRs with identical median household incomes may differ in their distribution of household income, i.e., HR B has greater income inequality.

Basic Categories

  • Geographic areas: public health unit, LHIN.

Indicator Comments

  • The “income inequality hypothesis” states that disparities in income among members of a community affect their health, and specifically, that economically egalitarian communities or societies have better health outcomes than more unequal communities.
  • Income inequality should be measured by a combination of indicators.  There is no one single measure of low income or income inequality, but there are measures that can be used in conjunction with others to provide some context to the income sphere (eg. Ginni coefficient, the ratio of 90% over 10% after tax income, the Survey of Labour and Income Dynamics (SLID), or share of income by quintile (bottom 4%, top 40%).  Statistics Canada recommends using the Gini coefficient. 
  • The Gini coefficient is a number between zero and one that measures the relative degree of inequality in the distribution of income.  The coefficient would register zero (minimum inequality) for a population in which each person received exactly the same adjusted family income and it would register a coefficient of one (maximum inequality) if one person received all the adjusted family income and the rest received none. Even though a single Gini coefficient value has no simple interpretation, comparisons of the level over time or between populations are very straightforward: the higher the coefficient, the higher the inequality of the distribution, and vice versa.
  • The Gini coefficient is not readily available below the level of the province of Ontario. 
  • The median share of income is one of the measures of income inequality that is readily available at the health unit level from Statistics Canada.
  • In low-income comparisons across time or across countries/regions, it is often more desirable to view low income in relative terms, as the low-income line is defined as some proportion of median or average income in respective time periods or regions.  

Cross-References to Other Indicators

  • Recommend to use median share of income with low income rate and with median household income.


  1. Sanga D. Income inequality within provinces. Perspectives on labour and income 2000;1(02):33-38.
  2. Weinberg DH. A Brief Look at Postwar U.S. Income Inequality. Washington: Bureau of the Census, Economics and Statistics Administration, U.S. Department of Commerce; 1996, June. Report No. P60-191. Available from: URL:
  3. Ross NA,Wolfson MC, Dunn JR, Berthelot JM, Kaplan GA, Lynch JW. Relation between income inequality and mortality in Canada and the United States: cross sectional assessment using census data and vital statistics. BMJ 2000;320:898-902.
  4. Wilkinson RG. Unhealthy societies: the affliction of inequality. London: Routledge, 1996.
  5. Lynch JW, Smith GD, Kaplan GA, House JS. Income inequality and mortality: importance to health of individual income, psychosocial environment, or material conditions. BMJ 2000;320:1200-1204.
  6. Mackenbach JP. Income inequality and population health. BMJ 2002;324:1-2.
  7. Statistics Canada. Data and definitions of income and low-income lines.  2009. Available at:
  8. Xi G, McDowell I, Nair R, Spasoff, R. Income inequality and health in Ontario: A multilevel analysis. Canadian Journal of Public Health 2005;9(3):206-211.
  9. Wong, CH. The Gini Coefficient of income disparity of Ontario by Census Divisions in 1996 and 2001. Public Health and Epidemiology Report Ontario (PHERO). 2003 Sep 30:130-5.  Available from:
Changes Made

DateType of Review – Formal Review or Ad Hoc?Changes made byChanges
January 2013FormalSocial Determinants of Health Subgroup·         Renamed from Income Inequality to Median Share of Income to align with Statistics Canada·         Revised definition provided·         New section on OPHS added·         Addition of Outcome, Assessment and/or Surveillance, and Protocol requirements related to this indicator·         Corresponding Health Indicators from Statistics Canada added·         CANSIM tables provided for Corresponding National Indicators ·         Data Sources updated to reflect new National Household Survey·         Added mathematical equation for  Median Share of Income·         Additional information on other ways to measure income inequality provided in the Indicator Comments section·         Cross References to Other Indicators added to reflect recommendation to use median income·         Addition of references pertaining to measures of income inequality·         All sections have been updated in alignment with the new Guide to Creating or Editing Core Indicator pages


Lead Author 
Contributing Author(s) 
Core Indicator ReviewersLead:  Luanne Jamieson, Hamilton Public Health ServicesWilliam Kou, York Region Community and Health ServicesCam McDermaid, Ottawa Public HealthVirginia McFarland, Grey Bruce Public HealthDinna Lozano, North Bay Parry Sound District Health Unit
External ReviewersElizabeth G S Rael, Ministry of Health and Long-Term Care, Health Promotion Division, May 27, 2013Sean Marshall, Public Health Ontario, May 30, 2013

 Last Updated: July 25, 2013

Previous Revision: May 23, 2006

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