On 16 June, Sir Robert Chote wrote to Munira Wilson MP in response to concerns about claims made by the Mayor of London regarding vehicle compliance with the Ultra-Low Emission Zone (ULEZ) in Outer London. In our letter, we stated that we were satisfied that the Mayor’s claim is consistent with the data collected by TfL at the time, namely that ‘nine out of 10 of those households in outer London who have a car are compliant’.
We wish to correct this reference. We are satisfied that data collected by TfL supports statements used in its press release that nine out of 10 cars seen driving on an average day in Outer London meet the ULEZ emissions standards.
As set out in TfL’s ULEZ compliance data additional information page, data on the compliance of households in Outer London who have a car are not available. Therefore, this statement made by the Mayor is not supported by publicly available data.
Dear Ms Wilson,
Thank you for your letter of 13 April raising concerns about claims made by the Mayor of London regarding vehicle compliance with the Ultra-Low Emission Zone (ULEZ) in Outer London and seeking clarity on whether it would be appropriate for the Mayor to publish the figures underlying those claims.
The Office for Statistics Regulation (OSR) has contacted the Mayor’s office and Transport for London (TfL), which assesses ULEZ compliance by cross-referencing camera images of number plates with DVLA records. We are satisfied that data collected by TfL at the time supports the Mayor’s claim that nine in 10 cars seen driving in outer London now meet ULEZ standards. However, data on households in outer London who have a car that meet ULEZ emissions standards are not available. The statement made by the Mayor relating to households in outer London is therefore not supported by publicly available data.
The data underlying the Mayor’s claim on cars driving in outer London were not available to the general public at the time, either from the Mayor’s office or from TfL. Users requesting clarification were provided with additional information, but that too was not made available on an equal basis to the general public. This is inconsistent with our principles of intelligent transparency and with the Code of Practice for Statistics. Like other organisations within the Greater London Authority, TfL voluntarily applies the Code as part of the Mayor’s commitment to transparency.
This case is one of several examples raised with us in which TfL has made statements or issued press releases based on unpublished TfL data or where data quoted are not provided with sufficient context. This prevents interested members of the public from being able to verify the figures, which can undermine trust in the organisations producing the analysis and their other outputs. While some additional information has now been published, I would urge the Mayor and TfL to make this material fully accessible to support understanding on what is a topic of high public interest.
By voluntarily applying the Code, TfL makes a commitment to producing analytical outputs that are of high quality and useful for supporting decisions. OSR has been engaging positively with analytical and communications colleagues in TfL who have been open to suggestions for improvements. TfL is working to further develop its understanding of the Code internally and OSR will continue to provide support and advice.
I am copying this letter to the Mayor of London and the following at TfL – Andy Lord (Commissioner), Howard Carter (General Counsel) and Matt Brown (Director of Communications and Corporate Affairs) to further support the case for the accessible publication of data used in public statements and press releases.
Sir Robert Chote