Wednesday, 25 April 2018

Correlation, causation, food banks and benefit cuts

"Spurious correlations" is a website created by the management consultant Tyler Vigen which delivers, magnificently, what its name promises. It shows a graphical correlation between the number of Americans who drown in swimming pools and the number of films in a year starring Nicolas Cage. 
The site features evidence that the number of murders by "steam, hot vapours and hot objects" moves in tandem with the age of Miss America. One particularly close relationship is the number of civil engineering doctorates awarded and the US per capita consumption of mozzarella cheese.
But the crowning glory of the website is a chart showing how the use of UK food banks shot up as the British state imposed benefit cuts on the least well off.
Actually, it isn't. There's no such chart adorning Vigen's site. But government ministers seem to feel this ought to be on his list of laughable correlations.
The Trussell Trust has announced that it provided Britons with a record level of emergency food supplies - 1.3 million - in the year to March 2018. That's up from just 3,000 in 2006. The number of supplies started rising rapidly around 2012, when government benefit cuts, enacted by the previous chancellor George Osborne, started to bite.
The charity says that the explosion in demand really is driven by benefit cuts, in particular the punitive new "sanctioning" regime, where benefits can be cut or withheld as a punishment for, say, missing appointments or failing to apply for enough jobs.
But the government denies it. "It's wrong to link a rise [in food bank use] to any one cause," said a spokesperson for the Department for Work and Pensions (DWP) when asked about the latest Trussell figures.
But what other "causes" could there be? The DWP does not elaborate, but a former minister at the department, Lord Freud, hypothesised a few years ago that it was actually a rising number of food banks which was stimulating demand. "Clearly food from a food bank is by definition a free good and there's almost infinite demand," mused the former investment banker.
Jacob Rees-Mogg advanced a related theory on his LBC radio show last year, claiming that food bank usage had shot up because ministers had changed policy and allowed job centres to inform people that the charitable resource existed: "The real reason for the rise in numbers is that people know that they are there and Labour deliberately didn't tell them," he said.
Maybe ministers are thinking of such explanations when they object to charities that suggest a link between their benefit cuts and soaring food bank use. Many will be tempted to take the analysis of charities, which actually distribute food to people and talk to them, more seriously than the airy theorising of various well-heeled Conservative politicians.
But we should respect the underlying serious message of Vigen's website. Correlation really doesn't automatically equate to causation and we should beware of taking charts at face value. Proving causation beyond doubt in the social sciences is nigh on impossible, but, at the very least, an observed association needs supporting evidence before we can talk confidently of one thing causing another.
So what evidence do we have in relation to food bank usage? Two academics from the University of Kent, Owen Davis and Dr Ben Baumberg Geiger, analysed pan-European survey data on food insecurity. They found that insecurity rose across Europe in the wake of the global financial crisis and associated recessions.
And the rise was especially stark in the UK.
This in itself should raise warning signs over the Freud/Rees-Mogg argument that people are using food banks not because something has got worse in their circumstances, but simply because they're there.
But what about the benefits link? Other researchers - Rachel Loopstra, Aaron Reeves, David Taylor-Robinson, Ben Barr, Martin KcKee and David Stuckler - have found that food banks are more likely to open in areas with higher unemployment rates and where local authorities have had greater aggregate cuts in welfare spending. There is also an association between higher local benefit sanctioning rates and the amount of local food parcels distributed. Analysis of the types of people who attend food banks shows they are much more likely to be on benefits or with low and precarious incomes.
The evidence is not conclusive, but it is highly suggestive. When government ministers and Conservative Party pontificators can produce a similar weight of evidence to support their own pet theories they will merit a hearing. Until then, we can file their views in a cabinet labelled "politically-motivated reasoning".
Now perhaps that would make for a good website…

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