Jonathan Portes: The pressure group playing fast and loose with evidence

Just yesterday, MigrationWatch published a report highlighting the "remarkable coincidence between the rise in youth unemployment and the huge surge in immigration from Eastern Europe over the last eight years".

But most published studies suggest immigration has little or no impact on employment or unemployment. Today's research supports that conclusion. For the first time, rather than using survey data, we use actual data on national insurance number registrations – the best and most comprehensive measure of people moving to this country to work.

We look at the number of registrations for each local authority and see whether there is any relationship between that and changes in the number of people claiming unemployment benefit.

As far as we can tell, there isn't any. Unemployment didn't rise faster (or fall more slowly) in areas where migration was higher.

Another issue is the impact of immigration during the recession. Again, we can't find any evidence of an adverse impact during periods of low growth or the recent recession.

What about the MigrationWatch report? As it says, between 2004 and 2011 an extra 600,000 Eastern European workers entered the UK labour force, while youth unemployment rose by 400,000. But most of that rise took place during 2008 and 2009, when the number of Eastern European workers fell. A "remarkable coincidence" – or how you would expect the labour market to respond?

This is not the first time MigrationWatch has played fast and loose with the evidence. So far the evidence suggests that other factors are far more important. As the Prime Minister has rightly said: "It's crude and wrong to say immigrants come to Britain to take all our jobs."

The author is director of the National Institute of Economic and Social Research and former chief economist at the Cabinet Office