REDUCTION OF EXPERIMENTAL ERROR IN COCONUT WITH ADJUSTMENT BY AN INTEGRATED INDEX DEVELOPED THROUGH PRINCIPAL COMPONENT ANALYSIS USING VEGETATIVE AND REPRODUCTIVE CHARACTERS

Precision in estimation and accuracy of the results from experiments is dependent on the nature of experimental variation. Controlling variation through calibration,. other than through local control, is a well defined concept since 1953. It is important that the choice of a calibrating variate or variates to be, cost effective, less time consumsing in recording, and efficient in reducing the experimental error. For experiments in coconut, one and two years pre-experimental yield is used as calibrating variates. Collecting yield data over a period of one or two  years to use as a calibrating variate is a long wait before commencement of an experiment: Financially too it is high. * This paper explores the merits of using, an 'Integrated Index' (incorporating the vegetative and reproductive characters) as a calibrating variate evaluated through the technique of 'Principal Component Analysis'. The characters were, .'Trunk Girth (X,)', 'Number of Inflorescences (Xj)', and Number of nuts per bunch (X3)', and 'Number of green fronds QQ\ The Integrated Index - I' developed through principal component analysis reflects the 'Vigour of the Pahn'. The eigen vectors of the four characters and the eigen values of the four vectors were evaluated through Principal Component Analysis. The standardized, vector scores for each palm was taken as the Integrated Index for each palm. The average of these values for a given experimental plot was taken as the Index for each.plot and was used as the calibrating variate. The results suggest that, the overall range in the values for the coefficient of variation' when adjusted for T was 7.05 to 10.78% as compared to the range, 8.35 to 21.02% observed without adjustment. The recording of variables X, to X« was completed within 3 to 4 days before the 53 commencement of the trial. Thus recording of the characters was less time consuming and cost effective.