It isn't possible to calculate precisely how many people are able to cover the recommended 85% of their pre-retirement income, but Federal Reserve data suggest that many people can't.

WSJ: Boomers Find 401(k) Plans Come Up Short

Of course, everyone knows that it is better to be number one than number two, but the Wallet Allocation Rule makes it possible to calculate precisely what this impact is.

FORBES: The Wallet Allocation Rule and Your Brand

Over time, as information was gathered, it is envisaged that it would be possible to calculate more precisely just what 1p of income tax actually raises in Scotland - and thus to expose the Scottish budget to the ups and downs of tax revenue.

BBC: Beware of Greeks bearing gifts