1. Indicator

(a)     Name: Average household size.

(b)     Brief Definition: Ratio of the total population to the total number of households.

(c)          Unit of Measurement: number of persons per household.

(d)         Placement in the CSD Indicator Set:  The indicator is part of the set of indicators of consumption and production patterns.  It is not included in the general CSD indicator set.

 2. Policy Relevance

(a)          Purpose: To monitor the number of persons per household.

(b)         Relevance to Sustainable/Unsustainable Development:  Household size affects the pattern of consumption of goods and services which could be shared among household members.  For example, in industrialized countries, decreasing household size is one of the factors causing an increase in per capita and aggregate energy use in residential buildings, including lighting, heating and fuel for cooking.  Other goods and services which may be affected by household size include water supply, solid waste disposal and household appliances.  The indicator, therefore, monitors an important factor, which may affect household consumption in the residential sector.

(c)         International Conventions and Agreements: None

(d)         International Targets / Recommended Standards: None. 

(e)          Linkages to Other Indicators:  The indicator is linked to other indicators of consumption patterns in the residential sector, particularly residential energy and water use per household or per capita.

3. Methodological Description

(a)                Underlying Definitions and Concepts:

·        Concepts of household:  In considering the links between the household size and the demand for residential services and the generation of household waste and other facilities, the differences between the housekeeping concept of household and the household-dwelling concept should be noted.  These two concepts are used in different countries.

               i.      Housekeeping concept: This concept of household is based on the arrangements made by persons, individually or in groups, for providing themselves with food or other essentials for living. A household may be either (a) a one-person household defined as an arrangement in which one person makes provision for his or her own food or other essentials for living, or (b) a multi-person household, that is to say, a group of two or more persons who make common provision for food or other essentials for living. The persons in the group may pool their incomes and may, to a greater or lesser extent, have a common budget; they may be related or unrelated persons or constitute a combination of both related and unrelated.

             ii.      Household-dwelling concept: In this alternative definition, used in many countries, a household  consists of all persons living together in a housing unit. Living quarters are classified into two broad categories:

a.      Housing units: A housing unit is a separate and independent place of abode intended for habitation by a single household, though it may be occupied by more than one households as defined by the housekeeping concept

b.      Collective living quarters:  Collective living quarters include structurally separated and independent places of abode intended for habitation by large groups of individuals or several households as defined by the housekeeping concept. Such quarters usually have certain common facilities, such as cooking and toilet installations, baths, lounge rooms and dormitories, which are shared by the occupants.  They include hotels, rooming houses and other lodging housing, institutions and camps.  Collective living quarters are generally excluded from data on household size, but they represent a very small proportion since 85 to 90% of people reside in housing units.

 ·        Household population:  There are two general frameworks within which individuals are identified: (i) households and (ii) institutions, as a subset of collective living quarters.  Household population, therefore, refers to the population living in households and should be distinguished from institutional population.  Institutional population includes persons living in military installations, correctional and penal institutions, dormitories of schools and universities, religious institutions, hospitals and so forth.

 More detailed information on the concepts and definitions of households can be found in Principles and Recommendations for Population and Housing Censuses, Rev.1 (United Nations, 1998).

 Detailed information on the definitions of households used by individual countries can be found in the Demographic Yearbook (United Nations, various years).

 (b)         Measurement Methods: The use of separate concepts for the household and living quarters has the advantage of providing an indication of groups of persons in need of separate dwellings. If, on the other hand, the household is defined as a group of persons occupying a set of living quarters, the number of households and the number of occupied living quarters will always be the same, and there will be no indication of the housing need in terms of doubled-up households requiring separate living quarters. Similarly, if living quarters are defined as the space occupied by a household, then the number of households will again be equal to the number of living quarters, with the disadvantage that there will be no record of living quarters existing but not in use.  In most countries, separate concepts of housing and living quarters are not used, leading to the same number of households and living quarters.

 The average size of households refers to the average number of persons per household. This rate is obtained

               i.      by dividing the total household population (i.e. excluding institutional population) by the number of households,  or

              ii.      as a weighted average ( or mean) of the household size weighted by the     proportion of households with a given number of members.

( i.e. average household size= 3 wi i, where wi  is the ratio of the number of households with i members to the total number of households.)

 The classification of the size of the household, based on the number of persons living in the household, is the following: 1,2,3,4,5,6,7,8,9,10 persons and over, and size of household not stated. The number of persons not living in a household and that of persons for whom no information is available are often available.

 (c)            Limitation of the Indicator: Statistics on the average household size are subjected to the qualifications set forth above (i.e varying definitions of the household and / or the living quarters) and on limitations in counting or estimating both the total household population and the total number of households.

 (d)        Status of the Methodology:

 (e)            Alternative Definitions / Indicators:

             iii.                              The average number of households per housing unit is obtained by dividing the total number of households by the total number of housing units. This indicator is a measure of the need for housing. However, the value is by definition 1 if housing units are defined as the space occupied by one household and the indicator is not useful.

            iv.                              The average number of persons per living quarters is the ratio of the total population to the total number of living quarters. The purpose of this indicator is to measure the crowdedness of living quarters. When data on population and living quarters are not available, this rate is approximated by the ratio of the  “population in housing units” to the total  “number of housing units”. 

4. Assessment of Data

(a)          Data Needed to Compile the Indicator:   

Population living in households

Number of households 

(b)     National and International Data Availability: The most important source of data on average household size is population censuses.

 The average household size has been compiled by the United Nations Statistics Division. The 39th issue of Demographic Yearbook (1987) gives various population statistics related to the size of the household. Table 30 gives the population in households, number of households and number of family nuclei by size of the households. Table 37 presents population in households by age and sex of householders, size of households and relationship to householder.  Table 38 shows households by age and sex of householder, by size and type of household, and by urban or rural residence. These statistics are shown for each census between 1975 and 1986

 (c)     Data References: 

 United Nations. Compendium of human settlements statistics, 1995

United Nations. Demographic Yearbook, 39th Issues- Special Topics: Household and family composition; 1987.

5. Agencies Involved in the Development of the Indicator

Lead Agency: United Nations Statistical Division, Department of Economic and Social Affairs (DESA).  The contact point is the Director, Statistics Division, DESA; fax no. (1 212) 963 9851.

 6. References

(a)                Readings:

United Nations. Principles and Recommendations for Population and Housing Censuses, Rev.1; 1998.

 (b)            Internet sites:

             United Nations Statistical Division:  http://www.un.org/Depts/unsd/