policymakers demonstrate

Population, Migration, Ageing and Health: A Survey 149
9. See Kirdar (2012) for an extension of the model in which outmigration is
endogenized.
10. This assumption ensures that factor returns are not affected by migration.
11. One important caveat to bear in mind though is that – as pointed out by the OECD
(2014) and the European Commission (2014b) – less than 40 per cent of the migrants
coming to the EU from outside the area gain access to it for work related reasons.
The most important channel is instead family reunification.
12. Shortages are therefore the result of a disequilibrium condition in which a labour
market does not clear.
13. Bottleneck occupations are defined at the ISCO 4 digit level and are ‘occupations
where there is evidence of recruitment difficulties, that is, employers have problems
finding and hiring staff to meet their needs’ (European Commission (2014b) Report
on ‘Mapping and Analysing Bottleneck Vacancies in EU Labour Markets’, p. 7).
14. The sample includes EU Member States, Iceland, Liechtenstein and Norway.
15. See Section 3.7 for a detailed analysis of the health sector.
16. For a recent proposal on the construction of an ‘optimal’ point-based system, see
by McHale and Rogers (2009).
17. Change of status is often allowed though, as in the case of the US H1-B visa programme.
18. Information is available for foreign trained and foreign citizen registered workers.
19. Holzmann and Koettl (2015) define portability as a mechanism to grant and transfer
social security rights independently of an individual’s country of residence, citizenship
status or current or previous occupation.
20. Article 1 of the European Union Council Directive 90/365 limits economically inactive
persons’ right to reside by two important conditions: ‘ … [that they] are covered
by sickness insurance … [and] … have sufficient resources to avoid becoming a burden
on the social assistance system of the host Member State during their period of
residence.’
21. An alternative definition used by some researchers is based on citizenship.
References
Ackers, L., and Dwyer, P. 2004. Fixed Laws, Fluid Lives: The Citizenship Status of Postretirement
Migrants in the European Union. Ageing and Society, 24, 451–475.
Adda, J., Dustmann, C., and Görlach, J. S. 2015. Migrant Wages, Human Capital Accumulation
and Return Migration. Unpublished manuscript.
Adserà, A., and Ferrer, A. 2015. Immigrants and Demography: Marriage, Divorce, and
Fertility. In: Chiswick, Barry R., and Miller, Paul W. (eds), Handbook of the Economics
of International Migration, vol. 1A. North-Holland, pp. 315–374.
Adserà, A., Ferrer, A., Sigle-Rushton, W., and Wilson, B. 2012. Fertility Patterns of
Child Migrants: Age at Migration and Ancestry in Comparative Perspective. The
ANNALS of the American Academy of Political and Social Science, 643, 160–
189.
Akresh, I. R. 2009. Health Service Utilization among Immigrants to the United States.
Population Research and Policy Review, 28, 795–815.
Andersson, G. 2004. Childbearing after Migration: Fertility Patterns of Foreign-born
Women in Sweden. International Migration Review, 38, 747–774.