Elementary Statistics and Computer Application

Optimum plot size

• Size and shape of experimental units will affect the accuracy of the experimental units. Select a plot with optimum plot size for this purpose. Minimum size of experimental plot for a given degree of precision is known as optimum plot size. Optimum plot size depends on crop, available land area, number of treatments etc.To determine the optimum plot size two methods are available. They are (1) Maximum curvature method and (2) Fairfield Smith’s variance law. For determining the optimum plot size in either method data are to be collected by conducting an Uniformity trial.


• An uniformity trial is a trial conducted over an experimental material by selecting a particular variety of a crop and for the entire experimental unit uniform treatments are given. At harvest, the experimental unit is divided into small basic units (depending on the crop) and yield recorded. Then to find the optimum plot size, the basic units are combined by adding the basic units in rows or columns. But while combining rows or columns no row or column should be left out. Then for the new units formed we calculate coefficient of variation and based on the CV values the optimum plot size is determined