> the data really isn't very well correlated It is however trivial to correlate - if there was a desire (or significant error) deemed it to be so. Of course b

> the data really isn't very well correlated It is however trivial to correlate - if there was a desire (or significant error) deemed it to be so. Of course basing your population estimate off the number of tax returns would "leave out some people" (>90% of the population of the uk for that example). Likewise basing it off the register of all children in schools would ignore most people over the age of 18. Ultiately the issue is that these people claim is rife is - all these undocumented people are getting all the jobs, benefits, healthcare, housing, government grants and school places which ignores the fact that to get any of those you have to be documented and registered on a myriad of systems to access that.