If trees are distributed at random in a wood the distance r from a tree to its nearest neighbour is such that the probability that it exceeds a is exp[-Ta/4], where is the mean distance. The following data (from E. C. Pielou, J. Ecol. 48, 575, 1960) give the frequencies of the nearest neighbour distances for 158 specimens of Pinus ponderosa. Test whether the trees may be regarded as randomly distributed and comment on your results. Distance to nearest neighbour Distance to nearest neighbour (in cm) 0-50 Frequency (in cm) Frequency 13 301-350 8 51-100 17 351-400 5 101-150 34 401-450 3 151-200 21 451-500 7 201-250 9 501- 14 251-300 17 Total 158 (Leic. Stat.)