PROBABLE LIMIT OF ERROR OF THE POINT DiSTANCE-NEIGHBOUR DI STANCE ESTIMATE OF DENSITY

(where t is Student's t, A is a measure of non-randomness, D is the estimate of density, and N is the number of sample points) and is considered to be analogous to the usual bounded plot sampling error formula tS/vN for the specific case where density averages one per plct. Using Student's t for the 95 percent level of probability, 90 percent of the density estimates, drawn from 40 computer-simulated populations were within the ranges given by the proposed formula. Similarly. 92 percent of 36 estimates obtained from 11 paper-dot populations and 76 percent of 93 estimates obtained from 25 natural populations were within the proposed PLE. In some of the remaining cases, the extent by which the proposed PLE's were less than the calculated difference between true density and D were quite trivial. Some anomalies probably arose from sampling difficulties.