Les retraites individuelles à long terme : une projection par microsimulation (version anglaise)

Didier Blanchet, Jean-Marie Chanut

Description

L'avenir des retraites est généralement envisagé en termes globaux : projection des grandes masses, des niveaux de prestations ou des taux de cotisations moyens. Ceci peut se faire à l'aide de modèles relativement agrégés. Mais l'évolution des retraites présente aussi des enjeux individuels : qui seront les individus les plus touchés par tel ou tel type de réforme, comment les modifications de droits interagiront-elles avec d'autres évolutions, telles que l'évolution des carrières individuelles, des structures familiales ? Un modèle de microsimulation dynamique est l'outil le plus adapté pour répondre à de telles questions. A partir d'un échantillon de données individuelles, représentatif de la population totale, il consiste à simuler le vieillissement des individus, tant du point de vue démographique qu'économique, ainsi que de leur droits sociaux. La construction d'un tel modèle est nécessairement progressive. Quelques résultats préliminaires illustrent la variété de ses utilisations potentielles, mais aussi l'importance des hypothèses qui les sous-tendent.

Sujets

• INSEE
• Retraite
• Salaire
• Économie
• Employabilité, métiers et formations

Informations

• Publié par: insee
• Nombre de lectures: 44
• Langue: English

Extrait

Individual Retirement Pensions
in the Long Run: a Projection
by Microsimulation*
The future of retirement pensions is usually considered in overall terms, with
Didier
projections of the main figures involved, average benefit levels and contribution
Blanchet
rates. These projections can be made using relatively aggregated models.
and
Yet the future of retirement pensions also raises personal issues: which individuals
Jean Marie
will be most affected by a given reform? How will changes in entitlements interact
Chanut**
with other developments in individual career paths and family structures?
A dynamic microsimulation model is the most appropriate tool for providing
answers to these questions. Using a sample of individual data that are
representative of the total population, it simulates the ageing of individuals,
both in demographic and economic terms, and their social entitlements.* Originally published as
"Les retraites individuelles
à long terme : une projec The construction of such a model has to be undertaken gradually. Some
tion par simulation," preliminary findings show the variety of potential uses for the model, as well as
Économie et Statistique,
no. 315, 1998 5. the importance of its underlying assumptions.
** Didier Blanchet was in
charge of the "Redistribu
tion and Social Policy" he dynamic microsimulation model For example, the impact of more restrictive
division of INSEE at the T presented here is mainly intended to conditions for entitlement to full pensionstime this article was writ
ten and Jean Marie project pensions, but we shall see that it cacalled for in the reform instituted n in the summer
Chanut works in the same also be used for broader purposes such as of 1993 will vary depending on individual
division. The current ver
projections of labour force participation career histories. New length of servicesion of the model is a test
version and the results are rates, family structures, etc. The reasons forrequirements (160 quarters) and new
given as an illustration undertaking this exercise are easy to under-entitlement calculations (with the switch to the
only. Since this article was
stand. Most of the thinking about the long 25 best years as the calculation basis) raise thewritten, work on the model
has continued under the term future of retirement pensions does notquestion as to whether the dispersion of
direction of Pierre Ralle. take on board the in house research work pensions will be wider or narrower, and by how
done by specific retirement funds and is much. Furthermore, even the average impact ofThe authors would like to
thank Anne Lafférère, based instead on macro demographic and the reform will depend on the dispersion in
Françoise Dumontier and macro economic tools. These tools can be individual situations, insofar as the schedules
Jérôme Accardo for sup
used to assess changes in average pensionsfor calculating pension entitlements are notplying the 1991 survey on
financial assets, and and the adjustments that may be required to straightforward linear scales.
Pierre Ralle for rereading prevent average pensions from falling too
this article.
far. But this type of result obscures the vaIsnt the same vein, we could look at how higher
Names and dates in variety of individual retirement situations, female labour force participation rates, longer
parentheses refer to the which more finely detailed analysis must life expectancy for men and women and
bibliography at the end of
take into account. changes in family structures will affectthe article.
INSEE Studies no. 37, August 1999 1women’s direct and derivative entitlements model itself in order to improve and diversify
and pensioners’ living standards. This wouldthe types of projections that can be produced.
require detailed analysis that takes into
account both past earnings and household
sizes. Detailed analysis is also required to The individual is the basic unit
study the redistributive impact of pension
systems within generations, and to assess theOut of the many surveys that could be used as a
effectiveness of measures to make systems starting point for microsimulation, we chose
more redistributive. the 1991 financial assets survey, which was
conducted between mid November 1991 and
When dealing with such issues, we soon early April 1992. This survey provides basic
encounter the limitations of conventional demographic data as well as information about
projection methods. These methods would careers (individual educational attainment,
require us to assume that the population can be years of service, earnings). It also provides
described by state vectors and large scale wealth and investment data, which have not
transition matrices that soon become too been used at this stage in the construction of the
complex to handle (see box). This is why model, but which could be added later to the
microsimulation appears to be the best choice.description of pensioners’ economic
It starts directly with a sample of individual circumstances, by providing the rate of home
data. Ageing and individual life paths are ownership for example. With a few
simulated by controlled random sampling adjustments, this survey provides an initial base
series and the renewal of the population by the of some 15,000 households containing some
arrival of new members is also simulated. Thi37,000 indis viduals.
method enables us to construct and maintain a
sample that we can then use to reproduce the Once the database has been chosen, there are
calculations carried out on the initial sample attwo possible ways to organise it. The choice
1 1Many examples of any future date. As long as the simulation between the two then determines how the
such models have been assumptions are valid and the sample is largsimulation program opee rates. The first
produced in other coun
enough to minimise the problem of stochasticpossibility is to make the household the unit oftries. See the surveys by
Harding (1990), Mot drift, we can envisage, for example, observation. Transitions in households are then
(1991) and Pennec distributions according to pensioners’ years ofsimulated by drawing samples for departing
(1994).
service, cross tabulated with their earnings andmembers and the arrival of new members. This
their marital status. These elements can then be approach makes it easier to calculate standard
used to establish a wide variety of data on of living directly for each household. On the
pensioners’ living standards. other hand, it requires computer processing of
rapidly changing structural records to simulate
There are three main steps in the development the dissolution and formation of households. It
of such a model. The first step is to set up the also requires embedded subprocesses. For
initial database, which is a file of personal example, simulating deaths and ageing requires
records providing information about how a subprocess for the population of households
individuals are connected to others by variousand a subprocess for each member of each
links of kinship and cohabitation. Such data are household. Moreover, the household based
important for analysing households’ living approach does not save us from having to deal
standards and for many other purposes. The with kinship connections between individuals
second step is to construct the simulation who do not live or who no longer live in the
program per se, which will enable us to same household. For example, we still have to
maintain the sample by introducing such lifetake account of adults’ connections to their
changes as marriages, births and deaths and aged parents and to their own children who are
social and economic changes such as leavingno longer living at home.
school, and entering and leaving the labour
force. The third step is to use the results toThe other possible way of organising the
analyse the individual data produced by database is to have a record for each individual.
simulation for each future period and to sumThe connections between them are then
them in indicators of averages, distributions, managed by a cross tabulation system. Each
etc. Of course, these steps are not fully record is flagged by an identifier and includes a
sequential. The first use of data from a set of variables that identify the other
primitive version of the model may be followed individuals connected to the individual through
up by further work on the initial data and on cohabitation or kinship (spouse, children andthe
2 INSEE Studies no. 37, August 1999 Box
DYNAMIC MICROSIMULATION AND CONVENTIONAL PROJECTIONS
1 Conventional projections (matrix methods)
Deterministic projection methods start with a description of the population in the form of an initial state
vector. This vector is in the Pt column showing the distribution of the population into a certain number of
classes. We assume that the transition from this state at time t to the state at time t + 1 can be simulated
by applying a transition matrix A to Pt, where the element aij is generally equivalent to the probability that
an individual in category j will end up in category i at time t + 1. This gives:
P = A P et P = A A ... A P .
t + 1 t t t + n t + n 1 t + n 2 t t
A projection of this type is therefore programmed as a matrix multiplication chain.
A typical case