Blocking

Summary

Blocking is the grouping of experimental units into blocks of similar units, with treatments compared within each block. Variation between blocks, such as differences between fields, days or batches of material, is then removed from the comparison of treatments. This makes the comparison more precise. It is the local control principle of design of experiments, and is usually combined with randomization inside each block. The randomized complete block design, Latin squares and balanced incomplete block designs are the standard block designs.