A Review of Block Designs for Test Treatments – Control(s) Comparisons

In practice there may arise experimental situations where it is desired to compare several treatments called the test treatments to a standard treatment called control. The main interest here lies in making test treatment-control comparison with as much precision as possible and comparison within the test treatments are of less importance. For example in agricultural experiments, the aim of the experimenter is to test a set of new varieties of a crop with an already existing variety and to determine which of the varieties perform better in comparison to the existing variety. Balanced Treatment Incomplete Block (BTIB) designs have been defined for this situation. The designs are balanced with respect to test treatment-control comparisons. The concept of BTIB is further extended to define Balanced Two Disjoint Sets of Treatments (BTDT) designs when there are more than one control. Some methods of constructing these designs are presented here. Some class of row-column designs, which are balanced for test treatments vs. control comparisons, referred to as the Balanced Treatment vs. Control Row- Column (BTCRC) designs are also described when heterogeneity is to be eliminated in two directions. Key words: Balanced Treatment Incomplete Block (BTIB) design; Balanced Two Disjoint Sets of Treatments (BTDT) design; Balanced Treatment vs. Control Row-Column (BTCRC) design. DOI: http://dx.doi.org/10.4038/jfa.v2i1.3939 JFA 2009; 2(1): 22-2