A NOTE ON DESCRIBING THE DECREASE IN A NEMATODE POPULATION

Abstract

The exponential model Y= [alpha]exp(-[beta]X) is commonly used to describe the decrease within biological phenomena. Four fitting techniques were compared in relation to the unbiasness and the variability of the estimates of the parameters. The applied techniques were: iterative solution for least squares, optimization of the likelihood, linearization, and linearization with weighting. It was shown that least squares and the likelihood always yields satisfactory results. Both of the other techniques could yield estimates deviating to a large extent from the parameters, depending on the rate of decrease.