ON THE YEH-BRADLEY CONJECTURE ON LINEAR TREND-FREE BLOCK-DESIGNS

Yeh and Bradley conjectured that every binary connected block design with blocks of size k and a constant replication number r for each treatment can be converted to a linear trend-free design by permuting the positions of treatments within blocks if and only if r(k + 1) = 0 (mod 2). This conjecture is studied. Results include: (i) the conjecture is true whenever the block size is even and (ii) the conjecture is true for BIB designs.