Robustness of connected balanced block designs
It is well known that the connected incomplete block designs with the highest intrablock efficiency factors are balanced. In a connected balanced block (BB) design, every elementary contrast is estimated with the same variance. If a treatment is lost in a connected BB design, then the residual design is not balanced for the most part. In this paper, an upper bound and a lower bound for efficiency of a residual design are derived with some illustrations. Moreover, from these discussions it is conceivable that the loss of efficiency even in the unbalanced case is, in general, small.
KeywordsBlock Design Original Design Efficiency Factor Balance Incomplete Block Design Balance Structure
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