Why British GDP figures are almost ALWAYS wrong.

Will it be 0.5 per cent? 0.8 per cent? 1 per cent? Whatever figure the ONS tells us GDP grew by in the third quarter of 2012, there’s one thing you can be pretty sure of: it won’t be the actual amount GDP grew by in Q3. In the past 51 years, just 12 of the ONS’s 205 first stabs at quarterly growth have survived later revisions. To be fair, the ONS recognises this, and cautiously labels tomorrow’s figure a ‘preliminary estimate’. But just how wrong is it likely to be? If tomorrow’s figure is +0.5 per cent, does that mean we can be pretty confident that growth was between, say, 0.3 per cent and 0.7 per cent — bad but not disastrous? It turns out we can’t. In fact, a preliminary estimate of +0.5 per cent really means somewhere between +1.2 per cent and –0.2 per cent — anything from encouraging to dire.