The news lifted hopes for a fast recovery in the UK. According to the Office for National Statistics (ONS) the construction activity in the UK had increased by 2.3% in the three months ending in June 2011. This was a manifold increase over 0.5% observed in the previous time periods. Within hours the economists all over the UK revised their estimates for GDP growth from 0.2% to 0.3%.
It was all fine until Alan Clarke, an economist with Scotia Capital noticed that if one averages the construction activity reported for April, May and June 2011, the result is a mere 0.5% increase and not 2.3% as the ONS had initially reported.
It turned out that an arithmetic mistake (i.e., simple addition, subtraction, division) caused the error.
Still not too late to send economists at ONS back for some refreshers in statistics.
ONS construction error moves markets - Telegraph