Efficiency of the Sample Variance for the Lognormal Distribution

Two unbiased estimators T and ?? of the variance ? = var (Y) of a lognormal distribution are considered. Here T is the sample variance and ?? is the minimum variance unbiased estimator of ?. The values of the ratio E = 100 var (??)/var (T) are tabulated for some values of the sample size n and of the coefficient of variation δ.