Principles of design of experiments-III: Local Control
This blog explains the concept of local control. ( reading time 6 min. ) There are three principles of designs of experiments: 1) Replication 2) Randomization 3) Local Control Replication and randomization alone can't remove the external influence of exogenous factors. So local control comes to the rescue. Local control is the grouping the experimental units into blocks such that within block there is homogeneity and between the block there is heterogeneity. The word block and replication are used interchangeably. By use of local control, between the block (replications) variations gets accounted into ANOVA and the experimental error gets reduced. Thus, local control is also termed as error control . Ideally, experimental error in an experiment is the measure of "within block (replication)" variation. In the field of agriculture research soil is the experimental unit. Blocking is done by technique of uniformity trials and soil fertility maps. L...