To paraphrase the old saying about statistics; it is a case of lies, dammed lies and surveys in the constant battle for mobile investment.

A case in point being last week's survey from the Brookings Institute which found that Dublin came eighth in a list of cities sending inward invest to the US. It came behind Tokyo, London, Paris, Toronto, Amsterdam, Rhine Ruhr and Brussels, according to the Washington based think tank, which has been dubbed the most influential of its ilk.

Some 141,000 US workers are employed in businesses funded by foreign direct investment coming out of Dublin, they say. It’s an impressive number and should ensure an even warmer welcome for the Taoiseach the next time he pops round the White House.

Unless the president's aides look closely at the Brookings study which identified the "accounting giant" Accenture, medical equipment supplier Covidien, building materials conglomerate CRH, and diversified industrial companies Ingersoll-Rand and Cooper Industries as being major sources of US-bound FDI out of Dublin.

The trouble is that only one of these companies is truly Irish – CRH – with the others being based here for tax reasons. Thus every time anybody orders a new photocopier in one of these companies’ US operations it counts as Irish FDI.

In fact, the less that is said about the Brooking report the better because it can only fuel to the already substantial fire burning in Washington about tax inversion deals which have seen US drug companies in particular decamp to places like Dublin to avail of low taxes.

It would surely only add insult to injury if the beltway types who are so exercised by all this realised that not only are they losing out on valuable tax revenue, but every time one of these companies spends money earned in the United States in it now counts as foreign direct investment from the Emerald Isle.