New report by the Commons Public Administration Select Committee criticises a number of aspects of the way migration statistics are calculated
Parliament's Public Administration Select Committee (PASC) has today released a report examining the migration statistics produced by the Office for National Statistics (ONS) and the Home Office.
You can read the report here.
According to a PASC press release, the committee found the statistics to be "blunt instruments for measuring, managing, and understanding migration to and from the UK."
The Chair of PASC and Conservative MP for Harwich and North Essex, Bernard Jenkin, described the statistics as being "little better than a best guess" and said they could be out by tens of thousands.
Annual estimates of immigration, emigration and net migration are primarily based on a sample of around 5,000 migrants identified and surveyed through the International Passenger Survey (IPS).
PASC says that the survey method is subject to a large margin of error, and the results are not accurate enough to measure the effect of migration on population, particularly in local areas, and they are not detailed enough to measure the social and economic impacts of migration, or the effects of immigration policy.
PASC also says that ONS and Home Office data are incompatible in several respects.
The Home Office statistics were criticised for not indicating the number of visa holders with valid leave to remain in the UK, or the number that overstay their leave to remain.
MP Bernard Jenkin said: "Most people would be utterly astonished to learn that there is no attempt to count people as they enter or leave the UK. They are amazed when they are told that government merely estimates that there are 1/2 million immigrants coming into the UK each year."
"This is based on random interviews of around 800,000 people stopped and interviewed at ports and airports each year. Only around 5,000 of those are actual migrants, many of whom may be reticent to give full and frank answers, to say the least."
Jenkin concluded that the statistics are clearly "not fit for purpose" in the longer term, and called for the improvement of the calculations to be given a much higher priority.
As we reported here, BBC News did an in-depth feature last year on the IPS method for calculating migration statistics. BBC News said that the government denies that the IPS is a faulty instrument for measuring its progress on migration, but the article concluded that, for now, net migration statistics should continue to be taken with a major dose of salt.