agronomic experimental design intervention design randomized complete block design A randomized complete block design is_a study design which assigns randomly treatments to block. The number of units per block equals the number of treatment so each block receives each treatment exactly once (hence the qualifier 'complete'). The design was originally devised from field trials used in agronomy and agriculture. The analysis assumes that there is no interaction between block and treatment. The method was then used in other settings So The randomised complete block design is a design in which the subjects are matched according to a variable which the experimenter wishes to control. The subjects are put into groups (blocks) of the same size as the number of treatments. The members of each block are then randomly assigned to different treatment groups.