The ONS updates its population projections every two years based on mid‑year population estimates but every ten years it can draw on the latest census results. Census 2011 suggested that there were around half a million more people in the UK in 2011 than assumed in the population projections at the time, among other compositional changes. This box outlined some of the key findings from the census data and the impact this might have on our future projections.

This box is based on Census 2011, ONS and Population Projections, ONS data from 2012 and 2012 respectively.

The ONS updates its population projections every two years, based on mid-year population estimates. Every 10 years it can draw on the latest census results. Census 2011 suggested that there were around half a million more people in the UK in 2011 than assumed in the latest population projections, which are based on 2010 data.a Census findings will be incorporated in new population projections later this year.

The Census results will affect population estimates back to 2001. These underpin various Labour Force Survey (LFS) measures (such as activity and employment rates) and may alter our view on the outlook for productivity, the labour market and eventually GDP growth. But an initial assessment of the impact on LFS aggregates for England and Wales in 2011 suggests that the effects are likely to be relatively small.b

Revised population estimates also affect the composition of the population that is projected into the future. The Census found more people of working age, especially women of childbearing age, and fewer people aged 75 and over. Updated population projections for England out to 2021, which mechanically fed through the implications without reviewing assumptions on specific fertility and mortality rates, projected a slightly larger population due to more births and fewer deaths.c

We will consider the impact of revised ONS population projections in future EFOs and FSRs, once those projections are available.

a ONS (2012c)

b ONS (2012d)

c ONS (2012e)