Confidence interval estimation of overlap: equal means case

The estimators of the commonly used measures of overlap are known to be biased by an amountwhich depends on the unknown overlap. In general it is difficult to calculate the precision or bias of most ecological measures because there is no exact formula for the variance of the statistic and the sampling distribution is unknown (Dixon, 1993. In: Scheiner, S.M., Gurevitch, J. (Eds.), Design and Analysis of Ecological Experiments. Chapman & Hall, New York, pp. 290-318.) Two resampling techniques, namely, Jackknife and Bootstrap along with the Taylor series approximation and transformation method are considered for the construction of confidence intervals. Three measures of overlap frequently used in quantitative ecology and considered in this study are Matusita's measure rho, Morisita's measure, lambda, and Weitzman's measure, Delta. (C) 2000 Elsevier Science B.V. All rights reserved.