nna {nna}

Calculates Spatial Pattern Analysis usisng a T-square sample procedure.

Description

Calculates Spatial Pattern Analysis usisng a T-square sample procedure.

Usage

nna(x, y)

Arguments

x

- Distance from the random point to the nearest individual

y

- Distance from individual to its nearest neighbor

Value

Returns the T-Square Index of Spatial Pattern (C); z-score of C; the Distance Index of Dispersion (I); and z-score of I

References

[1] Cottam, G., & Curtis, J. T. (1956). The use of distance measures in phytosociological sampling. Ecology, 37(3), 451-460. doi:10.2307/1930167 [2] Diggle, P. J., Besag, J., & Gleaves, J. T. (1976). Statistical analysis of spatial point patterns by means of distance methods. Biometrics, 659-667. [3] Johnson, R. B., & Zimmer, W. J. (1985). A more powerful test for dispersion using distance measurements. Ecology, 66(5), 1669-1675. doi:10.2307/1938029 [4] Lamacraft, R. R., Friedel, M. H., & Chewings, V. H. (1983). Comparison of distance based density estimates for some arid rangeland vegetation. Austral Ecology, 8(2), 181-187. doi:10.1111/j.1442-9993.1983.tb01605.x [5] Ludwig, J. A., & Reynolds, J. F. (1988). Statistical ecology: a primer in methods and computing (Vol. 1). John Wiley & Sons.

Examples

a=c(7, 19, 11, 18, 12, 27, 23, 27, 12, 8, 2, 4, 10, 18, 19, 8, 3, 9, 4, 5)
b=c(8, 6, 6, 13, 16, 11, 18, 8, 7, 7, 3, 7, 32, 22, 22, 12, 17, 18, 11, 10)
nna(a,b)