Figures showing industry slump in 2003 were actually distortions caused by computer glitch.

The Office of National Statistics (ONS) and the Department of Trade and Industry (DTI) have admitted that the 2.6% slump in the construction industry that it reported last year was caused by a computer error that deleted 65,000 firms from a list used to compile data and estimate output.

According to corrected figures, the sector grew by 0.5% in the first three months of 2003. The mistake led to more inaccuracy in the data for the second quarter, showing a leap of 5.3%, rather than the actual growth of 2.1%.

Mistakes made by statisticians had wide-ranging effects: based on the erroneous figures for the construction industry led to Britain’s overall economic growth being understated by 0.1% in the first quarter, and overstated by 0.1% in the second.