Trading insults about the accuracy of your opponents’ claims has become a staple of election campaigns, and the race to be London Mayor has been a prime example of this.

Both of the main candidates have accused the other of lying (occasionally in more colourful language) – so how do we know who and what to trust?

At a national level, we have the Code of Practice for Official Statistics. These important rules ensure that:

• Official Statistics used by government and politicians are also available to members of the public;
• Politicians and journalists that use Official Statistics do so in a fair way;
• Official Statistics are independently evaluated, and their limitations are made clear.

However while the Code covers central government and devolved assemblies, it doesn’t currently extend to the London Mayor or the GLA.

Unfortunately, this has meant that Londoners are frequently presented with poor quality information. For example, Full Fact found serious problems with the current Mayor’s use of transport crime and reoffending figures. (Having launched in 2010, we cannot comment on the previous Mayor's use of statistics).

Nor is the present arrangement deliberate. Sir Michael Scholar, the previous Chair of the UK Statistics Authority – the body charged with upholding the Code – wrote to Boris Johnson last year to ask that:

“in the interests of restoring public trust in government statistics, may I invite you to undertake in future to comply with the Code, as a matter of principle?”

With London set to elect its new Mayor in little over a fortnight, Full Fact has today written to each of the candidates to ask them to commit to the Code of Practice should they be the one to win the contest in May.

Politicians of various hues have been among those to echo this call, and we hope that each will work with us towards creating a more accurate and transparent administration in City Hall.

Follow us on Facebook or Twitter to keep up-to-date with the responses we get back.