Relationship between sampling intensity and precision for estimating damage to maize caused by rodents

Abstract

In this study we aimed to determine the relationship between sampling intensity and precision for estimating rodent damage. We used the systematic row sampling technique to provide data to achieve precision and accuracy in estimations of rodent damage in maize fields at the planting and seedling stages. The actual rodent damage to maize in 15 fields, each 0.5 ha in size, in Morogoro, Tanzania, was established at the seedling stage. These data were used to simulate the sampling intensities that would provide precision and accuracy. The variations between estimates were plotted against the sampling intervals. The results of this study show that the relationship between average standardized variances and sampling intervals is linear. The heterogeneous distribution of damage in some plots caused variations in the accuracy of the estimates between plots, but a sampling interval of five rows consistently produced estimates with a variance of less than 10%. We provide a standard curve that will allow a decision to be made on the sampling intensity as a function of required precision using the systematic row sampling technique in maize fields.