A new report from the Office for National Statistics (ONS) has revised net migration estimates from 2001-2011, and concluded that it was considerably higher than earlier estimates showed.
In particular, it showed net migration exceeding 200,000 in every year from 2004-2011, the years following the accession of eight new Eastern European countries (the A8) to the EU. The report, entitled Quality of Long-Term International Migration estimates from 2001 to 2011 suggests, in particular, that net migration was under-counted by more than 60,000 in 2005, 2006 and 2008.
The report considers which factors had led to the under-counting and suggests that the International Passenger Survey (IPS) – the key tool used in the development of the UK’s migration estimates – failed to respond quickly enough to changes in the routes into the UK that were used by international migrants. In particular, it did not respond fast enough the use of smaller airports and other ports of entry into the UK by migrants from Eastern Europe, and as a result they were under-counted.
The undercounting was discovered after the 2011 census implied that there had been net migration of nearly half a million more people into the UK than the LTIM (Long Term International Migration) estimates that are based on IPS data had previously indicated.
The Migration Observatory has been raising concerns about the reliability of data from the International Passenger Survey in developing accurate net migration estimates since our launch in 2011.
Dr Carlos Vargas-Silva, Senior Researcher at the Migration Observatory at Oxford University said: “We have known for some time that net migration must have been much higher during the 2001-2011 period than the official estimates had suggested. This report provides important evidence of the need for better migration data and of the limitations of using a survey to develop net migration data.”