SIMULATED SAMPLING STRATEGIES FOR NEMATODES DISTRIBUTED ACCORDING TO A NEGATIVE BINOMIAL MODEL

  • 1 January 1982
    • journal article
    • research article
    • Vol. 14  (4) , 517-522
Abstract
A FORTRAN computer program was developed to simulate nematode soil sampling strategies consisting of various numbers of samples per field, with each sample consisting of various numbers of soil cores. The program assumes that the nematode species involved fit a negative binomial distribution. Required input data are estimates of the mean and k values, the number of samples per field and cores per sample in the strategy to be investigated and the number of times the simulation is to be replicated. Output consists of simulated values of the relative deviation from the mean and SE to mean ratio, both averaged over all replications. The program was used to compare 150 simulated sampling strategies for Meloidogyne incognita, involving all combinations of 2 mean values (2.0 and 10.0 larvae/10 cm3 soil), 3 k values (1.35, 0.514 and 0.294), 5 different numbers of samples per field (1, 2, 4, 10 and 20), and 5 different numbers of cores per sample (1, 2, 4, 10 and 20). Simulations resulting from different mean values were similar, but best results were obtained with higher k values and 20 cores/sample. Relatively few 20-core samples were needed to obtain average deviations from the mean of 20-25%.