Randomized Complete Block Design (RCBD)

Description of the Design • Probably the most used and useful of the experimental designs. • Takes advantage of grouping similar experimental units into blocks or replicates. • The blocks of experimental units should be as uniform as possible. • The purpose of grouping experimental units is to have the units in a block as uniform as possible so that the observed differences between treatments will be largely due to “true” differences between treatments. Randomization Procedure • Each replicate is randomized separately. • Each treatment has the same probability of being assigned to a given experimental unit within a replicate. • Each treatment must appear at least once per replicate. Example Given four fertilizer rates applied to ‘Amidon’ wheat and three replicates of each treatment. Rep 1 Rep 2 Rep 3 A B A A=0 kg N/ha D A B B=50 kg N/ha C D C C=100 kg N/ha B C D D=150 kg N/ha