What is the Effect of Migration on Population Age Structure, Life Expectancy and Pension Burden in New Zealand?
Despite extensive literature search I can find no direct information or discussion of this question and I raise the following points in the hope that those more knowledgeable, can enlighten me.
I make the following assumptions:-
#1 Most immigration is of people above the age of 25
#2 Most immigrants are likely to have personal charactaristics which determine that their health and ‘education’ are above average for the population they leave
#3 Most immigrants from developing countries are likely to remain in New Zealand until retiring age or death
# 4 Some immigrants will bring older relatives to New Zealand
# Assumption #1 means that Life Expectancy and other data that is used to forecast Pension Burden is incorrect. This is because the cohort of the immigrant’s infant, child and early adult mortality did not happen in New Zealand and is omitted from the calculation. This means that at least, (and probably many more) 500 per 100,000 deaths in the infant, child and early adult category, are missing when calculating life expectancy etc. In a hypothetical group of 100,000 immigrants this would change their median age of death from 78 to a minimum of 78.4 years, and would increase with time and immigrant numbers. The larger the number of migrants the more this figure will skew the overall New Zealand median age of death upwards. I have used minimal figures and the effects are likely to be much larger, and as immigrant numbers increase, will have a significant statistical effect on the overall NZ life expectancy figures, to make make them appear larger.
# Assumption #2 means that immigrants may have health and other characteristics which means they may actually live significantly longer than NZ born inhabitants. Perplexing figures (to Americans) from the USA show that Hispanic immigrants live longer than US born inhabitants, despite having lower educational and financial status, which usually are associated with reduced longevity. A variety of contrived explanations, from a lower rate of smoking amongst Hispanics, to older Hispanics returning to their native land to die, have been postulated, but it would appear that self-selected individuals who emigrate are ‘fitter’ which to me as a Medical Scientist, is not surprising.
# Assumption #3 combined with Assumption #2 means that it is likely that immigrants will survive more years of ‘pensionable age’ than NZ born retirees.
# Once people are past their late sixties their chances of surviving another ten years actually increases, so that if Assumption #4 is correct, there will be an increasing Pension Burden for NZ for people who have not contributed to any tax or economic benifit.
I hope that somebody with expertise will provide actual figures to either refute or confirm my assumptions and conclusions, as they are a part of the Pension Burden debate which doesn’t seemed to have surfaced.
NB The effects described used to be partly balanced by emigration from New Zealand (although many were temporary emigrants). However, now that there is an increasing immigration surplus of of people who are likely to stay in NZ, the balance effect is disappearing.