Statistics body says some companies may be supplying new orders instead of output figures

Fresh concerns have been raised over the construction output data gathered by the Office for National Statistics after the body said not all construction firms fill in its surveys in the same way.

Graham Sharp, head of construction at the ONS, said some respondents to the survey, which generates output data, were putting down new orders or invoice data instead.

The news comes as the ONS took the unprecedented step of defending its construction data with a public briefing after criticism from industry groups. Critics say the large increases in output last year and steep fall this year have not truly represented the market.

If respondents are filling in the wrong data the risk is it that it will refer to the wrong month, as the new orders and output refer to different parts of the construction work cycle.

New orders are supposed to be measured in separate ONS figures to output.

Sharp said the lack of consistency in the way the survey is carried out gave “no systematic bias” to the results. He said: “Some information we’ve been getting would tend to lag the results, but others would have the opposite effect.

“We’d like to do some further analysis. Some firms may be struggling to give us the data we’re asking for.”

Sharp said the greater number of small firms contacted by the 8,000-firm ONS survey could be responsible for the more negative output figures this year that have knocked the UK’s overall GDP.

Noble Francis, chief economist at the Construction Products Association, said: “There is a question of what the ONS is actually measuring.”