Publication of the latest UK statistics brought gleeful reports of a reduction in net migration – the difference between immigration and emigration. But how reliable are the figures?
The Home Office had an unusual bit of good news last week: net migration fell from 252,000 in 2010 to 216,000 in 2011. This may still be a long way short of the government’s aim of driving it down into the tens of thousands, but for once the trend is downwards not upwards, even if Migration Watch predictably said they were a ‘disappointment’.
The Institute for Public Policy Research, equally predictably perhaps, said that the focus on net migration is very damaging, echoing Colin Talbot when he commented here on the drastic effects of the drive to get down student numbers on colleges such as London Metropolitan University.
But a more fundamental point is that the figures mean very little anyway. For a start, there is a massive variation around the net migration figure, which means that the published figure could be wrong by 35,000 either way.
Although the Office for National Statistics is now estimating the degree of uncertainty in the numbers, the headline figure is what grabs the headlines. Yet the recent ‘fall’ is only marginally outside the 95% confidence level for the net migration data. In other words, the fall might be non-existent or could in fact be much larger.
How does this arise? The Migration Observatory has recently published a brief guide to the ten main problems in migration statistics, which shows how fraught with inaccuracies they are.
Far from ‘counting people in and counting them out’, the government relies – especially when counting them out – on the very limited International Passenger Survey (IPS). Every year, about 200m people cross UK borders. The IPS is based on a sample of only 2,000 who are stopped at airports, with the obvious difficulties of getting a true random sample, gaining co-operation from people in a hurry or not keen to be interviewed, and so on.
In particular, someone who came to Britain from overseas, got married and became naturalised will be counted ‘out’ as a British citizen whereas they were counted ‘in’ as a foreign national, thus distorting both sets of figures. Slightly unbelievably, while the IPS asks people why they are leaving, it has only just started asking why they came in the first place.
As the Migration Observatory points out, this is only one instance of many severe weaknesses in migration statistics. For example, although there is only one method of measuring how many people leave the country, there are several for measuring how many arrive. However, they aren’t comparable with each other and produce wildly different figures.
The ones usually quoted – on long-term immigration – happen to be the lowest. The figure for non-EU immigration in 2010 was 284,000, based on the IPS already mentioned. But for the same year the number of non-EU visas issued was much higher – 538,000. The discrepancy is thought to be because of short-term visitors and people who get visas but don’t use them, but no one knows for sure.
Local migration statistics, which in the past have been the subject of much controversy, are if anything even more unreliable because they rely on sources such as the Labour Force Survey (LFS) which are not intended for this purpose. The Migration Observatory gives the example of East Devon, where the estimated number of foreign-born nationals is 4,000. But within the 95% confidence range, the true figure could be 8,000, or it could be zero! This does not exactly help local planning of public services.
As to the use made of those services by migrants, the statistics are pretty hopeless. Schools provide data on children who have English as a second language, for example, but of course they could have been born here and in any case they miss out migrants whose first language is English. Data on use of health services come only from whatever local studies might be carried out.
While we have reasonable data on the limited number of foreign nationals who enter social housing, we have none on their use of private renting except for what is available from the LFS, where housing is an incidental issue.
In short, migration statistics are a mess. Given the level of public and political interest in migration, and especially in magic numbers such as the rise or fall in net migration, this is rather surprising. A cynic might suggest it’s in politicians’ interests to have some headline figures to quote and they’re not really bothered whether they really mean anything.