Simple approximate variances for bletter values; a sampling enquiry. Supplement to Technical Report 269, Series 2

Estimates of the variance of certain linear combinations of order statistics (b-letter values) are proposed. The estimates are nonparametric and are quadratic forms in some order statistics. A heuristic justification of these estimates is provided. The performance of the estimates is judged from two sampling experiments. From the experiments the estimates are found to have a very modest bias and to adapt well to several sampling paradigms.