"The 500,000 Eastern European migrants that officials didn't know were here: So many entered UK that authorities lost track." The Daily Mail, 7 May 2013
Last year the census revealed a number of interesting facts about the growth in the number of foreigners in the UK. Recently it also emerged that according to the census, there are almost half a million more people in the country than previously thought.
The Daily Mail reported on the story today, suggesting that most, if not all, were migrants from Eastern Europe.
Are they right?
The official census estimate of the mid-2011 population of England and Wales is 56,171,000, which is 464,000 higher than the previous ONS estimates for 2011 of 55,707,000.
The Daily Mail reported that the official migration figures "missed out nearly half a million people who came to the UK after their countries joined the EU in 2004."
The ONS released a number reports on the matter: one July 2012, in September 2012, in December 2012, in February this year, and the last one on 30 April this year. They are all independent of each other - as an example only few of them are found on the same summary page - and yet they address the same point, albeit from different angles. The Daily Mail article seems to be based on the latest release.
However sometimes we need to refer than more than one report to get the full picture. As an example, last week's ONS release explained the 464,000 shortfall as "largely due to international migration, in particular an underestimate of the number of immigrants from the countries of central and eastern Europe that joined the European Union in 2004." The February release, suggests that this has actually been a long-term trend:
"The increased level of net migration during this period has resulted in migration maintaining a larger contribution to population change for more of the decade than in the rolled-forward series."
So how many are Eastern European migrants?
Last week's ONS report ('Methods used to revise the national population estimates for mid-2002 to mid-2010', page 3) includes a table which breaks down the factors explaining the difference between the mid-2011 census estimates and previous mid-2011 "rolled-forward" estimates.
In 2006, the European Union agreement on the free movement of persons was extended to eight countries, known as the EU8. These are Poland, Hungary, the Czech Republic, Slovenia, Slovakia, Estonia, Lithuania, and Latvia. As the table above shows, they comprise the biggest single factor in the number of individuals which were unaccounted for in the previous population estimates, totalling 250,000 individuals.
This figure was ommitted in the Daily Mail article, whose headline flags instead "500,000 Eastern European migrants that officials didn't know were here."
This 464,000 shortfall has been distributed across the decade, as this ONS table shows:
Why has this miscalculation occurred?
The short answer is that it varies depending upon component you chose to consider.
For example, the second biggest change relates to Ireland's "migration roll-back". What this means is that methods for estimating long-term migration to and from the Republic of Ireland were changed in the last few years. Though the ONS initially used data from the Irish Central Statistics Office (CSO), starting from 2009 data on migration from the Republic of Ireland came from the International Passenger Survey (IPS).
According to the December 2012 release, "250,000 immigrants from EU8 countries were missed completely, mainly due to limitations in the coverage of the International Passenger Survey (IPS) at that time."
The modelling approach
To determine the number of long-term migrants in the country, the previous estimates used a modelling approach which took national and regional immigration totals from the International Passenger Survey (IPS) and used a range of demographic, social and economic measures to model how many were likely to have gone to each Local Authority.
However, in November 2011, as part of its Migration Statistics Improvement Programme, the ONS published immigration totals using a new method for the years ending mid-2006 onwards.
In addition to this, the ONS goes on to explain that "estimates for the years ending mid-2006 to mid-2011 have been applied to the revised estimates, replacing the previous international immigration figures. However, for the years ending mid-2002 to mid-2005 the existing immigration flows have been retained as the administrative data required by the new method are not available."
While the ONS has added nearly half a million people to its latest population estimates, the Daily Mail headline claim that these were all "Eastern European migrants" isn't substantiated by the data.
Official figures from the ONS suggest around 242,000 of this total were migrants from EU8 countries; still the largest single factor, but around half of the half million claimed by the Mail.
Also, the Daily Mail's suggestion that the reason behind the shortfall was that "so many migrants flooded into Britain from Eastern Europe that authorities were unable to count them" (emphasis added) is contentious. While the ONS does mention limitations to the International Passenger Survey in tracking migrants, it was one of a number of factors that played into the revised modelling which has resulted in the larger figure.
Flickr image courtesy of mckibillo