Friday the 13th, accidents. The researchers in Exercise 23 also examined the number of people admitted to emergency rooms for vehicular accidents on 12 Friday evenings

(6 each on the 6th and 13th).

Year Month 6th 13th 1989 October 9 13 1990 July 6 12 1991 September 11 14 1991 December 11 10 1992 March 3 4 1992 November 5 12 Is Friday the 13th “unlucky”? Hospital emergency rooms need to plan for any increased “business” if they can. Use an appropriate nonparametric test to decide whether there is really a difference between consecutive Fridays when one of them is a 13th.