**Sankhya: The Indian Journal of Statistics**

1995, Volume 57, Series B, Pt. 3, pp. 420--427

**UNIVERSALITY OPTIMAL BLOCK DESIGNS UNDER A HETEROSCEDASTIC MODEL**

By

V. K. GUPTA, *Indian Agricultural Statistics Research Institute*

SUMMARY. The universal optimality of some block designs with unequal block sizes is studied under a certain heteroscedastic model. The C-matrix of a block design under the heteroscedastic model is obtained by using generalized least squares. Some methods of constructing universally optimal designs are given.

*AMS (1980) subject classification.* 62K05, 62K10.

*Key words and phrases*. Heteroscedastic model, generalised binary design, generalised least squares, universal optimality.