Any British citizen who bases his or her vote in the forthcoming general election on the “flash” official national income figures showing that output rose by 0.1 per cent in the final quarter of 2009 ought to be disenfranchised. These initial estimates are not exact enough even to say where in a range of plus or minus 1 per cent the change occurred. Later revisions – which go on for years after the period in question – could be in either direction. Our hypothetical citizen ought to be doubly disenfranchised if the intended vote is changed by similar decimal percentage point movement in the estimate for the first quarter of 2010 due a few weeks before the most likely date of the general election, May 6.

The fact is that estimates of real gross domestic product are not nearly accurate enough to measure fine changes. All that one can reasonably say is that output was roughly stable in the last quarter after having fallen by perhaps 5 per cent in the year as a whole. Even that is an optimistic assessment of what can be known. Ideally, one should take a moving average of several quarters, assuming that the direction of bias in the reporting has not changed radically. Taking everything into account, including recent surveys and other data, it looks as if the UK economy has stopped contracting.

Does that mean the recession is over? Yes, if you choose to define a recession in terms of falling output and keep your fingers crossed against the possibility of a double dip. But that gives us little insight. What surely matters is the gap between actual output and the trend consistent with non-inflationary growth. You may think that that is like looking for a black cat in a dark room; and in future articles I shall suggest a slightly different approach. Meanwhile, however, the Goldman Sachs UK Economics Analyst makes a heroic attempt to limit the range of argument.