Allergic even to the word 'research'

In today's column, Polly Toynbee writes:

The Institute for Public Policy Studies says migrants are profitable: for every £100 in taxes paid by the average British-born person, the average new immigrant pays £112. Migrants make up only 8.7% of the UK's population but pay 10.2% of its income tax.

I think she means the Institute for Public Policy Research -- their press release with these figures is here.  I have often chided Polly for failing to source facts and figures she uses.  It is encouraging to see her try to do so here, but it remains a case of high marks for effort; low marks for accuracy.

A recurring theme of Polly's piece is that migrants pull down wages.  So, for example, she argues that:

Even if GDP grows, migration can make the rich richer and the poor poorer. London, where migration is greatest, also has the highest unemployment, especially among British-born ethnic minorities. Poor families in this most expensive city can't pay for childcare, and compete for jobs with single migrants willing to take less than a living wage. But the rich prosper: restaurants, cleaners and all other services are cheaper because wages are low.

The argument suffers a little, as the IPPR figures on tax make clear that migrants tend to earn more than the average British-born person, and not less.  Indeed, the IPPR report behind the press release (pdf available here) shows that in 2003/4, the average gross weekly earnings from main job of working-age migrants was £405.83, compared with £355.06 for someone born in the UK.  To quote at length from page 7 of the IPPR report:

UK and foreign-born populations have slightly differing distributions of income. Immigrants are overrepresented at the upper end of the income spectrum. For example, some 4.7 per cent of the foreign-born working age population earn more than £1000 weekly compared to only 2.6 per cent of the UK-born. At the other end of the wage spectrum, where both immigrants and non-immigrants are more concentrated, there is a slight difference in the relative distribution. For example, at the very bottom end of the distribution, 12.8 per cent of UK-born earn less than £100 a week compared to 9.7 per cent of foreign-born. It is also worth mentioning that employment rates amongst immigrants are lower than those of non-immigrants (due in part to the fact that many foreign-born are students at British educational institutions)...