For dodgy credits, in any case, spreads are a poor guide to value, especially when yields are low.

ECONOMIST: The world's worst investment?

Instead of the usual ya-boo about sustainability, this is a pragmatic guide to getting more value from less stuff.

BBC: Go Figure: Why does every person need 200kg of steel a year?

The Economist's Big Mac Index, a light-hearted guide to how far currencies are from fair value, provides some answers.

ECONOMIST: Food for thought about exchange-rate controversies

Subsidising the vocational qualifications that employers say they value is supposed to guide people towards training that will lead to better jobs and higher pay.

ECONOMIST: Skills

The step-by-step guide to learning, and negotiating, your true market value, tomorrow.

FORBES: Exchange Your Unpaid Internship For a Job

The value, according to Bob Overstreet , publisher of the Overstreet Comic Price Guide, could be as high as half a million dollars.

FORBES: The Amazingly Profitable Spider-Man

The U.S. Environmental Protection Agency (EPA) has developed a formula to convert PM 2.5 readings into an AQI value that can help guide health-related decisions.

FORBES: Air Quality In China