Accuracy and precision of phytonematode sampling plans
Keywords:Action thresholds, berseem clover, citrus, economics, nematode distribution, rice
Sampling accuracy and precision are basic to nematode research and rational management decision. Taylor's Power Law is used to determine sample size. The published power law parameters are used here differently to define levels of reliability associated with a fixed, cost-determined, sample size. Such levels may provide the decision-maker with more informative data on sampling methods and their reliabilities. Instead of solving for unknown sample number, the rearranged equation to solve for sampling accuracy permitted the use of exact Student’s t-values. The t-values for confidence limits and standard normal variate were used. Both statistical techniques resulted in identical confidence band, in terms of being below, at, or above the economic threshold level, in the majority of cases. Reckoning with new trends in collecting and processing samples, a 99% confidence interval above action threshold of Tylenchulus semipenetrans population with mean = 2500 at a precision of 80% or more would be attainable.