ONS provides reliable view of growth, says chief economist But revisions can be made up to three years later. When you take these into account, just seven of the past 63 quarters remain unrevised. Such revisions have re-written economic history. Britain's so-called "double-dip" recession no longer exists, while many economists believe preliminary ONS estimates often paint a more pessimistic picture of the UK economy. Mr Grice disagrees. "We revise up about just as often as we revise down," he said. Quite a good example is the recession itself - our first estimate suggested the recession peak to trough was about 6.2pc. Now we believe it's about 7.2pc. We make revisions because we get more information over time. We have to make some estimates, or we wouldn't publish anything for three years. The ONS has drawn censure from several quarters, including Bank of England Governor Mark Carney, who suggested its data on business investment were unreliable. Several economists have also cast doubt over the accuracy of its latest retail sales data, which showed an annual jump of 5.3pc, but are at odds with reports of sluggish trading at several retail giants. Mr Grice, who spent most of his career at the Treasury before moving to the ONS, remains defiant. "We have never tried to pretend that the only information the Bank of England and Mr Carney should take into account is what they get from the ONS," he said. There's a whole range of information the Bank correctly takes into account - but on the whole the information we provide is reliable and gives a pretty good guide to what's going on in the economy. For all the criticism the ONS faces today, the quality of its data has improved vastly over the past two decades. Before 1989, statisticians simply took the three components of GDP growth - output, expenditure and income - added them up, and then divided the result by three. This over-simplistic method of calculating growth was criticised by the Treasury in 1988. It said it was "difficult to assess" the strength of the UK economy because equal weighting of the three measures created vast disparities between the output measure, which increased by 6pc in the first half of 1988, while expenditure had only grown by 2.5pc. In an perfect world, all three would grow at similar rates. This led to an overhaul of how GDP is calculated in 1989, known as the Pickford Review. Today, the Treasury still keeps tabs on the ONS to make sure it gets its sums right. Each quarter, officials from the Treasury, the independent Office for Budget Responsibility (OBR) and the Bank of England meet to quiz the ONS on its methodology. Mr Grice said he liaises with the Bank, Treasury and OBR "several times a week" to "put right any misconceptions" of its data. He also attends the Bank's pre-Monetary Policy Committee (MPC) meeting each month, a half-day affair held on the Friday before its rate-setting meeting. "We meet with [various officials] all the time," said Mr Grice. We understand the issues they're facing [and the meetings] give us the opportunity to put right any misconceptions.