Probability Range in Damage Predictions as Related to Sampling Decisions

  • H. Ferris


The risk involved in basing a nematode management decision on predicted crop loss is related to the uncertainty in the crop damage function and error in measuring nematode population density. The sampling intensity necessary to measure a nematode population with specified precision varies with population density. Since the density is unknown prior to sampling, optimum sampling intensity for a management decision is calculated for the economic threshold population level associated with the management cost. Population densities below the threshold are measured with greater precision than required; those above the threshold are less precisely measured, but invoke management. The approach described provides resolution to sampling strategies and allows assessment of the risk associated with the management decision. Key words: crop loss, management decisions, sampling intensity, risk analysis, economic thresholds.