In the early 1990s, a team of medical researchers at the Mid Downs Health Authority, West Sussex, set out to prove whether people really believe that Friday 13th is unlucky - and whether they are more prone to misfortune on that day. They analysed reams of official statistical data on road traffic flows, supermarket occupancy rates and accident and emergency hospital admissions. Their results, published in the British Medical Journal under the title "Is Friday the 13th bad for your health", were startling. They found 1.4 per cent fewer vehicles on the southern section of the M25 bewteen Junctions 7 to 10 on Friday the 13ths between 1990 and 1992 compared to the previous week. The weather was fairly similar each week - meaning, the researchers concluded, at least 1.4 per cent of the population "are sufficiently superstituous to alter their behaviour and refrain from driving on motorways on Friday the 13th". By contrast, they noted, the number of shoppers at nine Sainsbury's supermarkets rose by 0.9 per cent - suggesting superstition did not extend to a mortal fear of slipping in the frozen good aisle. But it was the data on emergency admissions that stunned researchers.
