A quick informal survey of the teachers, who had not had a meeting, revealed disappointment.

He did so by analysing thousands of ticket prices relative to the number of days before departure - a souped-up version of the informal survey he had conducted at 30,000ft.

An informal survey of residents in the affected area showed that slightly more were in favour of the wind farm than those who were opposed.

In an informal survey of three agencies with trunked systems that included this feature, users at two sites reported they did not think their system included the feature.

Moreover, based on an informal survey of the most accurate forecasters, it found that they were likely to use formal statistical models rather than pure judgment.