Indexes help us to understand the world. Since 1986, the Economist has published the Big Mac Index , which reveals discrepancies in exchange rates, using the tasty medium of the price of a Big Mac. Guido Fawkes has attempted to revive the Misery Index , which measures how unhappy we are by combining the rates of inflation and unemployment (plus the deficit divided by GDP).
David Cameron wanted a more optimistic measure and so attempted to launch a Happiness Index, to much criticism .
The latest index thought up by the Economist goes beyond economics, however, and looks at the turmoil in the Middle East. Behold, The Shoe Thrower's Index :
There are few surprises. Yemen, Libya and Egypt, Syria and Iraq top the list, while small, oil-rich, pro-western states in the Gulf are near the bottom. The only misplaced presences appear to be Jordan, whose government has been rocked by recent events in the region , and Tunisia, which triggered the turmoil  when a popular uprising removed President Ben Ali from power.
Here's how the Economist compiles the chart .
The chart below is the result of ascribing a weighting of 35% for the share of the population that is under 25; 15% for the number of years the government has been in power; 15% for both corruption and lack of democracy as measured by existing indices; 10% for GDP per person; 5% for an index of censorship and 5% for the absolute number of people younger than 25.
The events of the past few weeks have led to a flurry of speculation, not much of it evidence-based. The Shoe Thrower's Index goes some way to remedying this – albeit in a frivolous fashion. It's not foolproof, but it is fun.