What is a population projection?
Population projections provide an outlook of the potential future population, based on past indicators and prospective scenarios regarding three components of the population variation: fertility, death and migrations.
INSEE carries out demographic projections based on the results of population census. There are 3 types of projections:
- population projections: they are based on the latest population sizes per sex and age, and simulate the evolution of the number of men and women of each age every year until the projection horizon
- projections on households: those are the estimations on the number of households and mainly aim at evaluating the potential housing demand. They start with population projections, which are associated with hypotheses on the evolution of behaviours towards cohabitation
- labour force projections: they use population projections and business behaviour projections. They aim at understanding the future evolution of labour resources (proportion of economically active population available to contribute to the production).
What is Omphale?
Omphale is an application composed of a theoretical model of population projection, demographic databases & analytical techniques and prospective-oriented construction tools. The 2010 Omphale model enables population projections per sex and age in the long/medium term for every zone made up of an exact number of towns (provided it meets a 50,000-inhabitant threshold). Labour force and household projections can also be made by simply using sex and age rates (i.e. activity rate and proportion of household reference person). It should therefore be noted that a projection goes beyond a mere forecast exercise: it is a simulation that helps give a precise measure of what could happen if some assumptions were to be verified. Omphale 2010 allows users to incorporate many hypotheses that are of pure demographic nature since they are based on fertility, death and migrations.
Omphale 2010-based projections produced by INSEE have a 2042 horizon. They are based on data from the 2007 population census. They follow 3 steps:
- zoning constitution:
the zone on which projections are made needs to be defined by adding communal or supra-communal areas. Standard zones (regions, departments, employment areas, urban areas and urban entities) have already been defined in the tool.
- the choice of a scenario:
A scenario is a set of hypotheses on fertility, death and net migrations. 9 scenarios - which detailed assumptions are given below - are already predefined in Omphale.
Users can choose between two versions of INSEE projections:
- the light version - type 1 (P1) - contains 3 scenarios: a central scenario and two extreme scenarios ("high population"/ "low population")
- the complete version - type 2 (P2) - offers 9 scenarios (including the 3 scenarios of the light version)
Projections at infra-departmental levels must be systematically consistent with projections at the department level.
Which Pre-defined Scenarios Does Omphale Feature?
... remain at its 2007 level
... increase by 0.15 in 2015 (high fertility)
... decrease by 0.15 in 2015 (low fertility)
... grow at the same pace as metropolitan France's: 88.8 years for women and 83.1 years for men in 2040
... rise to 90.6 years for women and 84.9 years for men in 2040 (high life expectancy)
... or reach 87.1 for women and 81.4 for men in 2040 (low life expectancy)
... experience steady migration flows during the projection period
... have a +150,000 immigrant flow each year until 2040 (high immigration)
... have a +50,000 emigrant flow each year until 2040 (low immigration)
The 9 pre-defined scenarios in Omphale and the 2 proposed versions of projections by INSEE are the following:
|Scenarios||Chosen asumptions||Disseminated versions|
|Fertility||Life-expectancy||Migrations||Light (P1)||Complete (P2)|
By applying several scenarios for one single projection, it is expected that impartiality should be preserved. The two extreme scenarios (high and low population) that complement the central scenario aim at asserting the prospective dimension of the tool.
How to Define and Obtain Projections?
If you want to get a projection, you must submit a request via the Quetelet-Progedo Diffusion Data-ordering Application (reference APF-0003).
For the construction of the projection, you will then need to choose and tell us:
- the projected population (choice between individuals, households or members of the economically active part of the population)
- the projection zoning selection of communal and supra-communal areas to be combined; with a minimum threshold of 50,000 inhabitants in a given area). Please note that a zone can either be standard or be made of a set of municipalities. "Standard" zones are: France, one or several regions, one or several departments, one or several ZE 2010, one or several AU 2010, one or several UU 2010. If a zone is made up of a set of municipalities (non-standard zone), the municipality codes of this specific zone must be provided (in 5 characters exactly). If there are several zones, a code and a label must be provided in order to identify each zone.
- the scenarios based on selected assumptions (choice between two dissemination products: a light version (P1) with 3 scenarios or a complete version (P2) with 9 scenarios)
Once your request has been approved, INSEE will deal with it and send the results to Adisp, which in turn will forward them to you.
Result files will be provided for each year from 2007 to the projection horizon (i.e. 2042). As to population projections, 5 "result files" per scenario are issued. They relate to the population, births, natural population growth and net migrations. One single result file per scenario will be produced for the number of households or economically active persons. These files are delivered under the same conditions as those applicable to other Adisp-disseminated files; for legitimate research purpose only.
INSEE information to potential users
A recent change in the individual census record has made it impossible to update Omphale data entries until a new 5-year comprehensive cycle including the new residential migration issues be produced. The update of the Omphale application is expected to start by the beginning of 2017.
You will find on INSEE website a a detailed methodological documentation regarding the Omphale population projection model.