The information requested falls within the responsibility of the UK Statistics Authority. I have asked the authority to reply.

Letter from Glen Watson, dated May 2013:

As Director General for the Office for National Statistics (ONS), I have been asked to reply to your Parliamentary Question asking the Minister for the Cabinet Office when the Office for National Statistics will issue revised Long Term International Migration Statistics for the period between the 2001 and the 2011 censuses in line with its revised annual population estimates [155574]

The results of the 2011 Census enabled ONS to compare the census estimates with the mid-year population estimates. The population estimates use long-term international migration data as a component of the estimate. The comparison with census estimates led to revisions to the rolled forward mid-year population estimates from the year to mid-2002 to the year to mid-2010. This included a revision to the net migration component, focussed on the middle part of the decade before improvements were made to the International Passenger Survey in 2009. This provides a revised series of net migration for the inter-censal period.

Revised net migration figures published as components of change in revised population estimates can be found in table 10 at the following link:

http://www.ons.gov.uk/ons/rel/pop-estimate/population-estimates-for-england-and-wales/mid-2002-to-mid-2010-revised--subnational-/rft---mid-2002-to-mid-2010-revised-tables.zip

The information requested falls within the responsibility of the UK Statistics Authority. I have asked the authority to reply.

Letter from Stephen Penneck, dated September 2012:

As Director General for the Office for National Statistics (ONS), I have been asked to respond to your question concerning what level of reduction in UK net migration from 2010 to 2011 would have been regarded by the Office for National Statistics as statistically significant (121381).

On August 30, ONS published provisional estimates of Long Term International Migration (LTIM) for 2011. Estimates from the International Passenger Survey (IPS) are the main component used to calculate LTIM. As with all survey estimates, they carry a degree of uncertainty due to sampling variation. The uncertainty around the IPS based migration estimates was expressed as a confidence interval in this publication. A confidence interval provides an upper and lower limit in which we would expect the true value to lie with 95% probability.

These confidence intervals were published alongside inflow, outflow and net flow estimates. The change seen in the net migration estimates from 252,000 in 2010 to 216,000 (provisional) in 2011 was described as not statistically significant. This is because the confidence intervals for the IPS component for each estimate overlapped and the difference between the figures could have been due to sampling variation.

The 2011 provisional estimate for net migration would have needed to be below 180,000, for ONS to regard the change from 2010 as statistically significant. The upper limit of the confidence interval associated with an estimate below 180,000 is less than the lower limit of the 2010 estimate, so the confidence intervals do not overlap and the difference between the two estimates is considered to be statistically significant.

The information requested falls within the responsibility of the UK Statistics Authority. I have asked the authority to reply.

Letter from Stephen Penneck:

As Director General for the Office for National Statistics, I have been asked to reply to your Parliamentary Question asking for an estimate of the level of net migration per annum which would be required to stabilise the population of the UK below 70 million (109561).

The most recent national population projections, based on the resident population at the middle of 2010, were published by the Office for National Statistics (ONS) on 26 October 2011. Under the principal assumption of long-term annual net migration of 200,000, the UK population is projected to surpass 70 million people by 2027. ONS have not carried out any analysis to determine what level of net migration would be required for the population to stabilise below 70 million over the projection period to 2110. However, ONS has produced a number of variant projections based on alternative assumptions of net migration. Under the assumption of long-term annual net migration of 100,000 or less, the UK population would not exceed 70 million by 2035.

The assumptions underlying national population projections are demographic trend based. They are not forecasts and do not attempt to predict the impact that factors such as future government policies or changing economic circumstances might have on the population. The projections also become increasingly uncertain the further they are carried forward in time.