Projecting population

Projecting Population

Why does counting people up matter to governments? Peter Cheney looks at how Northern Ireland’s future population is estimated and some uses for the statistics.

Since Babylonian times, countries have counted their people in regular censuses. Our next one is next year. As well as these snapshots in time, governments also find it useful to look ahead and predict whether and by how much their populations will grow or decline in future.

Every two years, a population projection is brought out for Northern Ireland and the most recent, published in October 2009, covers the period 2008-2013.

Two years ago, the province was home to an estimated 1,775,000 people, a number set to pass the 1.8 million mark this year and reach 1.839 million by 2013. Such an increase (totaling 171,000) would be mostly down to natural growth, with an estimated 55,000 more births than deaths. At the same time, the province will be home to more older people, with an 11 per cent rise in the number of pensioners over those years.

Projections are based on three factors: mortality, fertility and migration.

It is assumed that mortality will continually improve i.e. go down by about 1 per cent per annum, in keeping with the trend over the last century. Statisticians allow for more deaths among older members of the population.

For fertility, the underlying assumption is that the average local woman will have 1.95 children in her lifetime. People are also expected to keep living longer, and more migrants will come to Northern Ireland than those leaving. Fertility fell from 3.12 in 1971 to 1.75 in 2000 but has modestly increased since then; the trend is not fully understood.

Migration tends to take place in the early working age e.g. when students go to Great Britain (see pages 86-87). Across all age groups, there is a general balance between flows from and to Britain. There was a spike in in-migration just after EU enlargement in 2004 and, while this trend has been decreasing, it will still result in a higher than usual figure. Around 10,000 more people would be coming here than leaving, up to 2014. Beyond this, the trend is expected to go down to a ‘surplus’ of 500 people per year.

When it comes to age, children are classed as people under 16, women pensioners aged 60 and over, and male pensioners aged 65 and over. Pension ages are expected to change over the next decade so these categories will probably shift. The remainder of the population are therefore ‘working age adults’.

One of the main problems going forward is that the number of working age adults will only slightly increase (3 per cent over 2008-2023) while the number of older people grows much more substantially (41 per cent over the same period). This trend will also pull up the population’s average age from 37.6 in 2008 to 40.4 years by 2023.

In reality, the divide is not so clear-cut; not all working age adults work and many older people will keep up a job. However, middle-aged adults normally support those younger or older than themselves. The number of children would go up by just 4 per cent at the same time. Around 2026, a new challenge will come up as the number of adults aged over 65 overtakes the number of children.

Relevance

Dr Ian Shuttleworth, from Queen’s University Belfast, points out that predictions have an obvious importance in health and education. Figures for younger people determine how the future number of places for children at school and the schools’ locations. Likewise, those for older people have implications for the number of hospitals or nursing home places.

“It’s important in other senses,” he adds. “At the level of a nation-state, it’s important in planning things like taxation and pensions.”

As the projections are simply estimates, they are almost always slightly ‘out’. The 2004-2008 projection, to cite one example, gave a number 1,748,000 for the end of that period, yet the 2008 mid-year estimate was found to be 1,775,000, due to more births taking place. Longer term estimates naturally have a higher margin of error.

However, the numbers do tell what is expected to happen based on existing trends. “I don’t think it’s a case that it really matters whether they are right or wrong,” he continues. “What they’re doing is giving an informed guess as to what happens in future.”

Demography, the statistical study of populations, is an academic discipline and also occasionally makes the news, though for different reasons in different places. The prospect of the UK’s population reaching 70 million in 2028 hit the headlines in October 2007 and the national press regularly focuses on how society will cope with an ageing population.

Traditionally in Northern Ireland, population comes on to the news and political agendas around census time, with plenty of commentary on the proportions of Protestants and Catholics. Shuttleworth thinks that the regional media should instead look at the broader picture, given the topic’s relevance.

“There seems to be a mismatch and unevenness in coverage of demographic issues,” he thinks.

“Religious and community issues tend to be rather more forefront than, say, issues to do with age structures and non-sectarian population issues.”

Starting year 2008 2013 2018 2023 2028
Population (at start) 1,775.0 1,839.2 1,895.6 1,945.8 1,985.8
Births 25.1 24.8 24.1 23.0 22.3
Deaths 14.2 14.1 14.6 15.5 16.8
Natural change 11.0 10.8 9.5 7.5 5.5
Net migration 1.8 0.5 0.5 0.5 0.5
Population (at end) 1,839.2 1,895.6 1,945.8 1,985.8 2,015.6
End year 2013 2018 2023 2028 2033

Source: NISRA, 2008-based population projections. All figures in thousands.
Births, deaths and migration figures per annum.

Demography in practice

agendaNi contacted all the Executive departments to see how the figures are used.

The Department of Finance and Personnel uses them “widely” e.g. in economic appraisals for building schools and hospitals, and importantly the Barnett consequential which works out how much money Westminster gives Northern Ireland.

DRD’s uses include the housing growth indicators and projections for future travel demand, both from passengers and drivers. The Northern Ireland TripEnd Model (TEMPRO NI) estimates traffic levels going up to 2031. DARD’s application is in rural development, anticipating the number of people living in the countryside.

Health affects everyone and the stats can help DHSS officials work out locations for new facilities, so they can reach the most people. Recent work has been carried out for radiotherapy and renal services. Likewise, projections for pupils in schools are calculated by the Department of Education.

DSD has focused on the ageing population, looking at projected population due to reach pension age to assess how pay and back pay affect pension benefits. Household projections, also used by DRD, and forecasts for benefit uptake are also examples. The Department for Employment and Learning uses the projections to analyse flows into and out of the future working age population, which in turn affects the employment rate.

On the more creative side, DCAL uses them to set the stock of library books and also to plan ahead for community festival funding.

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