A new petition claiming the government's use of statistics on benefits is misleading has attracted more than 16,000 signatures.

You're more likely to click 'sign' online than grab a biro and clipboard these days. So perhaps it's no surprise that the petitions listed on change.org have attracted more than 165 million signatures from 196 countries. What may be surprising is that one of the site's latest petitions simply asks people to support the following:

This is ultimately a debate about whether the government's welfare reform programme will drive those who can to find jobs, or drive those who can't to despair. Numbers are going to be critical in showing which of those forces is more powerful, and consequently, in predicting the success or failure of reform.

Iain Duncan Smith ('IDS' above), the Work and Pensions Secretary has claimed that "the benefit cap sets a clear limit for how much support the welfare state will provide – the average wage for working households".

A trial, started last month in four of London's local authorities (Bromley, Croydon, Enfield and Haringey), was therefore a natural focus for the reform's supporters and opponents alike - and their respective number crunchers.

Graphic by Datablog. Click to embiggen.

On the day the trial began, the Department for Work and Pensions released 'ad hoc statistics' claiming that '8,000 claimants identified as potentially capped households' were now in work. It wasn't long (less than 24 hours) before David Cameron was hailing "a big day for welfare reform" and IDS was telling the Daily Mail "this clearly demonstrates that the cap is having the desired impact".

The figure was immediately subject to skepticism. Jonathan Portes, Director of the National Institute of Economic and Social Research (and previously chief economist at the Cabinet Office) was quick to point out that there was "no evidence at all" that the benefits cap was responsible for those individuals now having jobs.

The argument made by Portes and others boils down to one of the most basic principles in statistics: correlation does not prove causality. In other words, the fact that 8,000 would-be capped claimants are now in work does not demonstrate the effectiveness of the cap unless it can be proven that the threat of the cap influenced their decision to seek, and subsequently accept, work.

As Portes notes, this missing link does not necessarily disprove the government statistics either:

It may be that the benefit cap has indeed had the effect that Iain Duncan Smith would like it to have. That is perfectly possible but without doing the analysis – and it has not been done – you simply cannot say that and you shouldn't say it.

The issue also highlights the disconnect between politicians and some government analysts, economists and statisticians. The fact that the original release explicitly mentions in the notes that "it is not intended to show the additional numbers entering work as a direct result of the contact" shows how political sound bites can undermine the rigour of the original data collection.

Frustrated by the way these statistics have been used, Jayne Linney and Debbie Sayers started their petition on change.org. Both disabled, both disability activists, the pair state "we are concerned that this is just the tip of the iceberg". Their fears that "Smith has built a wall of misinformation to discredit all claimants" have so far been supported by 16,900 signatories since it was started five days ago and will eventually be presented to the Work and Pensions Committee.

The TUC, also angered by what they claim is "a bad policy that has to be promoted in such an underhand way" are calling on the UK Statistics Authority to investigate Iain Duncan Smith.

Watch employment minister Mark Hoban defending the trial of the benefit cap in London below.

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