Reported in today's "The Week" - from a book called "Nudge! Nudge!" by Richard Thaler and Cass Sunstein.

'Managers at Amsterdam's Schiphol airport, eager to reduce cleaning costs in the men's loos, had a fly drawn on the porcelain of each of the urinals - a behavioural nudge that has improved the accuracy of penile aim by 80%.'

There's no information on how the measurements were carried out.

Phil