The index of industrial production (IIP) for April was revised to 2.3 per cent from 2 per cent. On Wednesday,the data showed power generation grew by 0.7 per cent in April. However,the growth was pegged at 4.2 per cent today. Last year,the ministry of statistics and programme implementation had overestimated the IIP figure for January 2012 at 6.8 per cent against the actual 1.1 per cent. The correction was made only in April. The gaffe was due to the wrong calculation of sugar output,which was overestimated at 134.08 lakh tonnes instead of 58.09 lakh tonnes.