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4. Mortality Assumptions, 2012-based National Population Projections This product is designated as National Statistics

Released: 06 November 2013 Download PDF

Introduction

This report provides detailed information on the principal and variant mortality assumptions used in the 2012-based national population projections. The long term mortality assumption for the UK projects life expectancy at birth to be 84 years for men and 87.3 years for women in 2037.

Principal Assumptions

The mortality rates for the first year of the projection, from mid-2012 to mid-2013, are based on the best estimates that could be made in the autumn of 2013 of the numbers of deaths at each age in 2012-13. Assumed improvements in mortality rates after 2012-13 are based on trends in mortality rates before 2012.

The assumptions used in the 2012-based projections are that annual rates of improvement in mortality rates would converge to 1.2 per cent for most ages in 2037 (the 25th year of the 2012-based projections), and remain constant at 1.2 per cent a year thereafter. However, those born after 1922 and before 1939 have exhibited greater rates of improvement over the last 25 years than those born on either side. There is currently no evidence that these differentials are declining.  Similar cohort effects seen in other countries suggest that these differentials may persist well into the oldest ages.  As a result, it is assumed that these cohorts will continue to experience higher rates of improvement after 2037 with the assumed rate of improvement in 2037 and beyond rising from 1.0 per cent a year for those born in 1922 to a peak of 2.5 per cent a year for those born in 1931 and 1932 and then declining back to 1.2 per cent a year for those born in 1939 and later. For those born before 1922, rates of improvement are assumed to be lower than 1.2 per cent in 2037. Rates of improvement are assumed to decline further from 1.0 per cent for those born in 1911 to 0.1 per cent for those born in 1902 and earlier. These are the same assumptions for the rates of mortality improvement in the target year as those used in the 2010-based projections (where the target year was 2035).
 
Over the 49 year period 1960-62 to 2009-11, the rates of improvement were around 1.6 per cent per year for males and 1.4 per cent per year for females.  These rates of improvement are derived from aggregate mortality rates for ages 0 to 99 calculated using the 2011 population estimates for England and Wales as the standard population. The rate of improvement over the latter half of this period was higher than over the first half, particularly for males.  This appears to be partly due to differential trends in smoking behaviour between males and females.  Relatively higher numbers of men have now given up smoking and mortality rates for males at older ages have shown large rates of improvement in recent years.

The average annual rate of improvement over the whole of the 20th century was around 1.2 per cent for both males and females although the improvement rates vary by age. There is considerable debate as to whether the impact of future technical, medical and environmental changes will have a greater or lesser effect on improvements in mortality in the future than they had over the 20th century.

The transition from current rates of mortality improvement by age and gender, derived from recent trends, to the assumed rates of 1.2 per cent to 2.5 per cent in 2037 is not assumed to take place linearly, but more rapidly at first for males and less rapidly for females. There is growing evidence of generational effects for those born after 1940. Thus, in these projections, convergence to the assumed rate of improvement in 2037 has been calculated by cohort for all those born before 1960.  For those born in 1960 and later, for whom there is little evidence of generational effects, the changes in the rates of improvement to the target rate are projected by calendar year.

The rates of improvement after 2037 are assumed to remain constant (by cohort or by age, as described above) at the rate assumed in 2037 for each year thereafter. Taking account of the generally higher rates of improvement assumed prior to 2037, this produces average annualised rates of mortality improvement of around 1.5 per cent for males and females over the projection period to 2087 (75 years), which is around 0.2 per cent a year higher than those experienced over the past 75 years for both males and females.

The same future rates of improvements have been assumed for all countries of the UK except for some differences (generally, slightly smaller improvements) in the period to 2037 at some ages for males and females in Scotland, as has been done in recent past projections.

In 2037, period expectation of life at birth for the UK is around 0.4 years higher than in previous projections for males and 0.1 years higher for females compared to the previous projections. These differences are mainly due to a combination of the changes in initial rates of mortality improvement and base mortality rates, the change in the target year and the assumed interpolation of the rates of improvement between 2012 and 2037. After 2037 the life expectancies for males converge to those in the 2010-based projections whilst those for females fall to around 0.2 years lower. 

Period expectations of life at birth and at age 65, based on the projected mortality rates, are shown for selected future years in Table 4-1. A summary of the assumed percentage rates of mortality reduction for some specimen years and ages is shown in Tables 4-2 and 4-3.


Table 4-1: Period expectation of life at birth and at age 65 according to mortality rates assumed for selected years

years
Period expectation of life at birth
2012 to 2013 2016 to 2017 2026 to 2027 2036 to 2037
Males Females Males Females Males Females Males Females
England 79.0 82.6 80.6 84.2 82.8 86.1 84.3 87.5
Wales 77.9 81.8 79.8 83.5 82.0 85.5 83.6 86.9
Scotland 76.5 80.3 78.0 82.1 80.3 84.0 81.9 85.4
Northern Ireland 77.9 81.9 79.4 83.4 81.7 85.4 83.3 86.8
United Kingdom 78.7 82.4 80.3 83.9 82.5 85.9 84.0 87.3
Period expectation of life at age 65
2012 to 2013 2016 to 2017 2026 to 2027 2036 to 2037
Males Females Males Females Males Females Males Females
England 18.4 20.8 19.6 22.1 21.3 23.7 22.5 24.8
Wales 17.8 20.2 19.1 21.6 20.8 23.2 22.0 24.4
Scotland 17.1 19.3 18.2 20.6 19.9 22.2 21.1 23.3
Northern Ireland 18.0 20.3 19.1 21.6 20.8 23.2 21.9 24.3
United Kingdom 18.3 20.6 19.5 21.9 21.1 23.5 22.3 24.7

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Table 4-2: Assumed percentage reduction in death rates, mx, between calendar years for England, Wales and Northern Ireland

Percentage
2012 to 2013 2016 to 2017 2026 to 2027 2036 to 2037 Reduction over 25 years
Age last birthday Males Females Males Females Males Females Males Females Males Females
0 2.62 2.60 2.28 2.32 1.58 1.69 1.20 1.20 36.1 37.1
2 3.13 2.79 2.67 2.48 1.72 1.76 1.20 1.20 39.4 38.5
12 4.50 2.99 3.71 2.64 2.09 1.83 1.20 1.20 47.4 39.9
22 4.82 3.14 3.96 2.76 2.17 1.88 1.20 1.20 49.2 41.0
32 2.90 1.14 2.50 1.15 1.66 1.18 1.20 1.20 37.9 25.6
42 0.43 1.30 0.62 1.28 0.99 1.23 1.20 1.20 20.0 26.9
52 3.32 2.20 2.81 2.00 1.77 1.55 1.20 1.20 40.6 34.1
62 1.74 1.56 1.68 1.40 1.77 1.53 1.20 1.20 35.0 31.1
72 2.98 2.45 3.05 2.38 1.37 1.29 1.20 1.20 37.8 34.1
82 3.96 3.63 2.98 3.08 1.86 1.71 1.20 1.20 40.9 40.1
92 1.78 2.06 2.32 2.19 2.35 2.47 1.20 1.20 41.5 41.5

Table notes:

  1. Projections are made for calendar years, except figures in bold where projections are made by cohort.

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Table 4-3: Assumed percentage reduction in death rates, mx, between calendar years for Scotland

Percentage
 2012 to 2013  2016 to 2017  2026 to 2027  2036 to 2037  Reduction over 25 years
Age last birthday Males Females Males Females Males Females Males Females Males Females
0 2.62 2.60 2.28 2.32 1.58 1.69 1.20 1.20 36.1 37.1
2 3.13 2.79 2.67 2.48 1.72 1.76 1.20 1.20 39.4 38.5
12 3.82 2.99 3.20 2.64 1.91 1.83 1.20 1.20 43.6 39.9
22 4.13 3.14 3.43 2.76 1.99 1.88 1.20 1.20 45.4 41.0
32 1.08 0.17 1.11 0.37 1.17 0.84 1.20 1.20 25.2 16.7
42 0.02 1.05 0.31 1.08 0.88 1.15 1.20 1.20 16.6 24.8
52 3.49 2.20 2.94 2.00 1.81 1.55 1.20 1.20 41.6 34.1
62 1.95 1.56 2.05 1.40 1.82 1.53 1.20 1.20 37.1 31.1
72 2.66 2.23 2.88 2.24 1.50 1.29 1.20 1.20 37.5 33.1
82 3.51 3.36 2.70 2.84 1.79 1.65 1.20 1.20 38.8 38.5
92 1.66 1.90 2.19 2.03 2.25 2.37 1.20 1.20 39.8 40.0

Table notes:

  1. Projections are made for calendar years, except figures in bold where projections are made by cohort.

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Figure 4-1 shows the estimated and projected period expectation of life at birth for males and females in the UK between 1981 and 2087.

Figure 4-1: Estimated and projected period expectation of life at birth, United Kingdom, 1981-2087

Figure 4-1: Estimated and projected period expectation of life at birth, United Kingdom, 1981-2087

Notes:

  1. Data are displayed on a calendar year basis.
  2. Figures for 2002-2010 are due to be revised to take account of the 2011 Census for Scotland. Revised population estimates for Scotland and the UK for 2002–2010 were not available at the time of projection.

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Figures 4-2 and 4-3 show estimated and projected period expectations of life at birth for males and females for the constituent countries of the UK between 1981 and 2062.

Figure 4-2: Estimated and projected period expectation of life at birth, males, 1981-2062

Figure 4-2: Estimated and projected period expectation of life at birth, males, 1981-2062

Notes:

  1. Data are displayed on a calendar year basis.
  2. Figures for 2002-2010 are due to be revised to take account of the 2011 Census for Scotland. Revised population estimates for Scotland for 2002–2010 were not available at the time of projection.

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Figure 4-3: Estimated and projected period expectation of life at birth, females, 1981-2062

Figure 4-3: Estimated and projected period expectation of life at birth, females, 1981-2062

Notes:

  1. Data are displayed on a calendar year basis.
  2. Figures for 2002-2010 are due to be revised to take account of the 2011 Census for Scotland. Revised population estimates for Scotland for 2002–2010 were not available at the time of projection.

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Assumptions for Mortality Variants

Current annual improvements in mortality rates vary considerably by age and sex. For mortality, it is assumed that for most ages these improvements will gradually converge to common 'target rates' of improvement, at each age and for both sexes, by the year 2037, and continue to improve at that constant rate thereafter. However, it is also assumed that those born in the years after 1922 and before 1939 (cohorts which have consistently experienced relatively high rates of mortality improvement over the last 25 years) will continue to experience higher rates of mortality improvement than the rest of the population. 

The target rate assumptions are as follows:

  • High variant: 2.4 per cent annual improvement at 2037, thereafter annual improvement remaining at 2.4 per cent. For those born between 1925 and 1938 rates of annual improvement in and after 2037 will rise to a peak of 3.7 per cent a year for those born in 1931 and 1932 and then decline back to 2.4 per cent a year for those born in 1939 or later.

  • Principal projection: 1.2 per cent annual improvement at 2037, thereafter annual improvement remaining at 1.2 per cent. For those born between 1925 and 1938 rates of annual improvement in and after 2037 will rise to a peak of 2.5 per cent a year for those born in 1931 and 1932 and then decline back to 1.2 per cent a year for those born in 1939 or later.

  • Low variant: 0 per cent annual improvement at 2037, thereafter mortality rates remaining constant. For those born between 1925 and 1938 rates of annual improvement in and after 2037 will rise to a peak of 1.3 per cent a year for those born in 1931 and 1932 and then decline back to 0 per cent a year for those born in 1939 or later.


Table 4-4 shows period expectation of life at birth in 2037 that result from the principal and variant assumptions.

Table 4-4: Period expectation of life at birth in the year ending mid-2037 for the standard variants

High Principal Low
Males
England 86.4 84.3 82.2
Wales 85.7 83.6 81.4
Scotland 84.2 81.9 79.6
Northern Ireland 85.5 83.3 81.1
United Kingdom 86.2 84.0 81.9
Females
England 89.3 87.5 85.7
Wales 88.8 86.9 85.1
Scotland 87.4 85.4 83.5
Northern Ireland 88.6 86.8 84.9
United Kingdom 89.1 87.3 85.5

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Figure 4-4 shows estimated and projected period expectation of life at birth for the UK between 1981 and 2087 for the principal projection and the high and low variants.

Figure 4-4: Estimated and projected period expectation of life at birth, United Kingdom, 1981-2087

Figure 4-4: Estimated and projected period expectation of life at birth, United Kingdom, 1981-2087

Notes:

  1. Historic estimates are displayed on a calendar year basis while projected assumptions are displayed on a mid year basis.
  2. Figures for 2002-2010 are due to be revised to take account of the 2011 Census for Scotland. Revised population estimates for Scotland and the UK for 2002–2010 were not available at the time of projection.

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The equivalent figures for the constituent countries of the UK can be found in the relevant chart section.

 

Background notes

  1. Revised population estimates for 2002-2010 based on the 2011 Census are not yet available for Scotland so assumptions have been set using mortality rates for Scotland over this period based on estimates rolled forward from the 2001 Census. Analysis of the 2011 Census results has not highlighted any concerns with taking this approach.

    More information on the differences between the 2011 Census and the mid-year estimates for 2001 for Scotland can be found in the NRS reconciliation report at http://www.gro-scotland.gov.uk/statistics/theme/population/2011-census-reconciliation-report/index.html.

  2. Details of the policy governing the release of new data are available by visiting www.statisticsauthority.gov.uk/assessment/code-of-practice/index.html or from the Media Relations Office email: media.relations@ons.gsi.gov.uk

    These National Statistics are produced to high professional standards and released according to the arrangements approved by the UK Statistics Authority.

Appendix A: England Charts

Figure 4-1: Estimated and projected period expectation of life at birth, England, 1981-2062

Figure 4-1: Estimated and projected period expectation of life at birth, England, 1981-2062

Notes:

  1. Data are displayed on a calendar year basis.

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Figure 4-4: Estimated and projected period expectation of life at birth, England, 1981-2087

Figure 4-4: Estimated and projected period expectation of life at birth, England, 1981-2087

Notes:

  1. Historic estimates are displayed on a calendar year basis while projected assumptions are displayed on a mid year basis.

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Appendix B: Wales Charts

Figure 4-1: Estimated and projected period expectation of life at birth, Wales, 1981-2062

Figure 4-1: Estimated and projected period expectation of life at birth, Wales, 1981-2062

Notes:

  1. Data are displayed on a calendar year basis.

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Figure 4-4: Estimated and projected period expectation of life at birth, Wales, 1981-2087

Figure 4-4: Estimated and projected period expectation of life at birth, Wales, 1981-2087

Notes:

  1. Historic estimates are displayed on a calendar year basis while projected assumptions are displayed on a mid year basis.

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Appendix C: Scotland Charts

Figure 4-1: Estimated and projected period expectation of life at birth, Scotland, 1981-2062

Figure 4-1: Estimated and projected period expectation of life at birth, Scotland, 1981-2062

Notes:

  1. Data are displayed on a calendar year basis.
  2. Figures for 2002-2010 are due to be revised to take account of the 2011 Census for Scotland. Revised population estimates for Scotland for 2002–2010 were not available at the time of projection.

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Figure 4-4: Estimated and projected period expectation of life at birth, Scotland, 1981-2087

Figure 4-4: Estimated and projected period expectation of life at birth, Scotland, 1981-2087

Notes:

  1. Historic estimates are displayed on a calendar year basis while projected assumptions are displayed on a mid year basis.
  2. Figures for 2002-2010 are due to be revised to take account of the 2011 Census for Scotland. Revised population estimates for Scotland for 2002–2010 were not available at the time of projection.

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Appendix D: Northern Ireland Charts

Figure 4-1: Estimated and projected period expectation of life at birth, Northern Ireland, 1981-2062

Figure 4-1: Estimated and projected period expectation of life at birth, Northern Ireland, 1981-2062

Notes:

  1. Data are displayed on a calendar year basis.

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Figure 4-4: Estimated and projected period expectation of life at birth, Northern Ireland, 1981-2087

Figure 4-4: Estimated and projected period expectation of life at birth, Northern Ireland, 1981-2087

Notes:

  1. Historic estimates are displayed on a calendar year basis while projected assumptions are displayed on a mid year basis.

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