The Efficiency of pre-experimental yield in the calibration if coconut experiments

The coefficient of variation of experiments with mature coconut palms in respected of the character 'yield' varies from 11perc. to 15 perc. when the plot size varies from 18 palms to 6 palms. The experimental precision in higher in years when the cropping intensity is high. There is also a tendency for the experimental precision to improve as the experiment ages and with increased plot size. With the use of pre-experimental yield as a calibrating variate the experimental error can be reduced by 30perc. to 50perc.. Two year's pre-experimenta yield brings about a higher reduction in experimental error than using one year's, and using more than two year's pre-experimental yield does not help. In fact when one takes into consideration the delay caused by keeping pre-experimental records, and the cost involved, one year's pre-experimental records could be considered the optimum. In view of the fact that even with 6-palm plots, the coefficient of variation can be kept within 10perc. with the aid of calibration, there is a strong case for reduction of plots size in coconut experiments