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Dynamic microsimulation, Methodology

Research articles · Apr 30, 2025

SimPaths: An open-source microsimulation model for life course analysis

Patryk Bronka, Justin van de Ven, Daniel Kopasker, Srinivasa Vittal Katikireddi, Matteo Richiardi

Centre for Microsimulation and Policy Analysis, Colchester, United Kingdom; MRC/CSO Social & Public Health Sciences Unit, Glasgow, United Kingdom

Volume 18(1) Spring 2025

Cite as: P. Bronka, J. van de Ven, D. Kopasker, S. Katikireddi, M. Richiardi; 2025; SimPaths: An open-source microsimulation model for life course analysis; International Journal of Microsimulation; 18(1); 95–133. doi: 10.34196/ijm.00318

Abstract

The paper introduces SimPaths, an open-source framework for individual and household life course events. The framework is designed to project life histories through time, building up a detailed picture of career paths, family (inter)relations, health, and financial circumstances. The modular nature of the SimPaths framework is designed to facilitate analysis of alternative assumptions concerning the tax and benefit system, sensitivity to parameter estimates and alternative approaches for projecting labour/leisure and consumption/savings decisions. SimPaths builds upon standardised assumptions and data sources, which facilitates adaptation to alternative countries – models based on the framework currently exist for the UK, Greece, Hungary, Italy, and Poland, and are under development for Germany, Spain and Sweden. Projections for a workhorse model parameterised to the UK context are reported, which closely reflect observed data throughout a validation window between the Financial crisis (2011) and the Covid-19 pandemic (2019).

This article contains 24 figures and 2 tables.

Figures

Figure 1. Structure and order of processes modelled in SimPaths.
Figure 2. Student status.
Figure 3. Educational attainment
Figure 4. General health score, men.
Figure 5. General health score, women.
Figure 6. Psychological distress, men.
Figure 7. Psychological distress, women.
Figure 8. Partnership status.
Figure 9. Number of children.
Figure 10. Activity status.
Figure 11. Employment rates, men.
Figure 12. Employment rates, women.
Figure 13. Real wages, trend.
Figure 14. Real wages, distribution.
Figure 15. Hours worked.
Figure 16. Gross income, trend.
Figure 17. Gross income, distribution.
Figure 18. Income sources, value.
Figure 19. Income sources, share.
Figure 20. Equivalised disposable income.
Figure 21. Disposable income, distribution.
Figure 22. Poverty.
Figure 23. Inequality.
Figure 24. Correlations.

Tables

Table 1. List of modules and estimated processes.
ModuleProcess
AgeingAge increases.
Probability of leaving the parental home for those who have left education. (Students stay in the parental home).
EducationProbability of remaining in education for those who have always been in education without interruptions.
Probability of returning to education for those who had left school.
Level of education for those leaving education.
HealthSelf-rated health status for those in continuous education.
Self-rated health status for those not in continuous education (out of education or returned having left education in the past).
Probability of becoming long-term sick or disabled for those not in continuous education.
(Mental Health (1)) Level of psychological distress on GHQ-12 Likert scale and binary case-based indicator of psychological distress.
(Mental Health (2)) Effect of exposure to employment-state transitions, household income change, and poverty for individuals aged 25 – 64 on psychological distress (GHQ-12).
Family compositionProbability of entering a partnership for those in continuous education.
Probability of entering a partnership for those not in continuous education.
Probability of partnership break-up.
Probability of giving birth to a child.
Social careProbability of needing care for individuals over an age threshold.
Probability of receiving care for individuals under an age threshold with a disability or long-standing illness or over the age threshold, distinguished by formal, partner, son, daughter, and other providers.
Hours of care for those in receipt of care, and financial cost for those receiving formal care.
Probability of providing informal social care.
Hours of informal social care, among those providing care.
Investment incomeProbability of retiring for single individuals.
Probability of retiring for partnered individuals.
Probability of receiving capital income for those in continuous education.
Probability of receiving capital income for those not in continuous education.
Amount of capital income for those in continuous education.
Amount of capital income for those not in continuous education.
Amount of pension income for those who are retired and were not retired in the previous year.
Labour incomeHeckman corrected wage equation; females not employed last period.
Heckman corrected wage equation; males not employed last period.
Heckman corrected wage equation; females employed last period.
Heckman corrected wage equation; males employed last period.
Hours worked, single males.
Hours worked, single females.
Hours worked, single male adult children.
Hours worked, single female adult children.
Hours worked, males with dependent partner.
Hours worked, females with dependent partner.
Hours worked, couples.
Disposable incomeBenefit recipiency indicator.
Amount of disposable income.
Consumption & savingConsumption.
Home ownership.
Savings and assets.
Statistical displayEvaluate summary statistics for simulated population.
Table 2. Relationship between state variables in SimPaths.
Dependent variable
Control variablestudent statuseducation levelhealth statusmental healthdisability statuspartnership statusfertilitychildcare costhome ownerretirement statuspension income (£)capital income (£)low wage offerpotential wage (£)hours workedneed social carereceive social caretype of care receivedamount of care receivedprovide social careamount of care provided
gendercccccccccccccccccccc
ageccccccccccccccccccc
educationllcccc,lccccccccccccccc
maternal educationcclc
paternal educationccc
partnership statuslc,lllc,lclcllccccccc
number of childrenllllllclllc
age of childrenlllc
health statusllc,lc,lclllccccccc
mental healthl
disability statusllllcc
need social carel
receive social carel
type of care receivedlc
amount of care received
provide social carelc
amount of care provided
activity statusllc,lllclllllc
hours workedcc,l
disposable income (£)lc,lllllc
employment income (£)l
benefit income (£)c
capital income (£)lll,l2
pension income (£)lll, l2l,l2
potential wage (£)llll
home ownercl
regioncccccccccccccccccccc
yearcccccccccccc

Note: Each column reports the controls used to update a specific individual characteristics.