TY - JOUR T1 - Use of Pretreatment Information in Design of Experiments. I. Nearly Optimum Designs for Covariance Models JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. SP - 174 LP - 177 DO - 10.5344/ajev.1980.31.2.174 VL - 31 IS - 2 AU - S. Geng AU - M. B. Carter AU - J. O. Johnson AU - S. K. Perng Y1 - 1980/01/01 UR - http://www.ajevonline.org/content/31/2/174.abstract N2 - Pretreatment information about experimental units is often available for agricultural experiments. This information has been used primarily for adjusting treatment response at the stage of data analysis, whereas its use to improve the experiment is seldom discussed. If a covariance model can be established to represent the relationship between data collected before and after the treatment, a procedure is proposed for construction of nearly optimum designs to minimize the generalized variances of treatment means. The procedure is illustrated by allocating grapevines (Vitis vinifera L.) to two and four treatments based on pretreatment measurements of pruning dry weight and volume of aboveground structure of plants. It is shown that the group means are well balanced after the directed allocation. ER -