The Office for National Statistics has defended its construction industry data, saying it offers the “largest and most comprehensive” measure of the industry’s output.
Industry economists have suggested the data does not properly reflect performance after the output measure was changed to monthly rather than quarterly, and new orders quarterly rather than monthly.
But the ONS said its survey offered the largest and most comprehensive measurer of construction output, considering a range of construction firms, from those employing fewer than four people to firms with more than 100 and turning over tens of millions of pounds.
It said: “Dialogue with businesses does not indicate any systematic difficulties in completing their return that would bias the series in any particular direction as a result of the improvements made in 2010.”
It added: “A number of sources for data are used to complete our questionnaires. This will not have changed as a result of the improvements introduced in 2010.
The Q1 2011 data showed companies employing fewer than four people saw output growth fall by 9.7 per cent compared with Q4 2010. Those with at least a £60m turnover and 10-99 employees saw output drop 25 per cent, while companies employing more than 100 people saw a 4.3 per cent fall.
The monthly output survey is based on a sample of 8,000 businesses each month.
The ONS mentioned surveys from the Royal Insitution of Chartered Surveyors, the Chartered Institute of Purchasing and Supply and the Mineral Products Association, but said “many surveys ask whether business is up, down or the same over the last period and do not account for company size”.
Despite this, the ONS also noted planned improvements, such as routine checks on questionnaire content and further checks on sources of data used.
Its definition of construction encompasses construction of buildings, infrastructure work and civil engineering projects, along with glazing, scaffolding, demolition, test drilling and boring.
Output used to be reported on a quarterly level, but has been changed to monthly to “improve timeliness for output to GDP”.
New orders were being reported monthly but and now reported quarterly to “reduce the burden on businesses”.