The household projection model projects changes in the number of households of different sizes (from 1 to more than 7), as well as changes in the number of people living in such households by age, education level, and the rural/urban residency status of the household head. The model is based on an extended household headship rate (likelihood of population to head a household) method.
It converts the multidimensional population projection results into household projections through incorporating household headship rates by various demographic characteristics. Compared to the conventional headship rate method, the CDM’s extended household projection model additionally incorporates headship rates by education level and rural/urban status that are proved to be equally important in assessing socioeconomic and environmental impacts of demographic changes.
Headship rates are typically derived from population censuses or national sample survey data. The user can either assume headship rates of the base year to be unchanged in the future or apply dynamic headship rates for projection years. To achieve consistent population and household projection results, the household projection model scales initial headship rates to ensure total population sizes over time from the household projection model are identical to the original population projection inputs.
The current model includes household projections for several global regions that are consistent with the SSPs. The headship rates of the current regions are derived from their population censuses and national household income and expenditure surveys.
The user can also import their own data based on the SSPs or alternative scenarios after following some formats to produce household projections for their region of study accordingly.