Blackwell Science Ltd. Further electronic distribution is not allowed. It is the ratio of mean crowding of a population to its mean density. The mean crowding is defined as the mean number of neighbors per individual per unit area.
Individuals are neighbors if they are taken in the same sample.
A patchiness index that is not a function of the population density is ideal because it permits comparisons of patchiness between years with varying abundance and over different life stages. Since the mean crowding is averaged over individuals, it is unaffected by samples taken outside the natural range of the organism which contain no individuals. However, the mean population density would be reduced with these zero-count samples included. Therefore the patchiness index would rise. On this scale, Lloyd's index of patchiness would be large.