A motion agreed by all parties on the Assembly says “there should be complete transparency around any statistics used by the Mayor of London, the London Assembly and the Greater London Authority.”
It goes on to note “concern” at the Mayor’s “unwillingness” to adopt the Code following accusations that he misused statistics.
Last year London Assembly Members and MPs raised concerns over the Mayor’s use of “misleading” statistics about re-offending rates at the City Hall backed Heron Unit within Feltham Young Offenders’ Institution.
The Mayor’s claims over current policing numbers have also been repeatedly questioned.
The UK Statistics Authority previously expressed concern over Johnson’s use of figures and he has faced repeated calls to sign up to the Code of Practice.
However in December 2011 Johnson told Labour’s Joanne McCartney “I do not think it appropriate for the GLA to sign up to the Authority’s Code”.
When subsequently asked by other AMs to review his stance Johnson has referred questioners back to that response.
The Mayor has also faced accusations by Assembly Members of making statements designed to be “deliberately misleading by omission”.
Last month Johnson announced a new data ‘dashboard’ accessible online and via screens at City Hall.
The service will bring together information from Greater London Authority bodies, allowing Londoners to see “up-to-date” data about crime, transport performance, jobs, health and the environment.
AMs say the creation of the dashboard means it’s important Londoners have “maximum confidence” in City Hall’s published data and statistics.
Stephen Knight AM, who proposed the motion, said: “The Mayor has said he thinks public trust in statistics is critically important in a democracy yet he has continually refused to sign up to the UK Statistics Authority Code of Conduct. Worse, the Mayor has had to be admonished by the Authority for the misuse of figures.
“The Code of Conduct underpins integrity, honesty and objectivity in the provision of the data on which we build our political arguments and assess solutions to the problems our city faces. As every government department has signed-up to this good practice I cannot understand why the Mayor is so reluctant to commit to do the same.”