readily available from a number of sources, e.g., Anderson and Houseman (1942) and Fisher and Yates (1957). When the factor of interest is quanti- tative, but not equally spaced, simple tables do not exist. Under such cir- cumstances, computer algorithms such as those given in Robson (1959), Gaito (1965), Tadikamalla (1974), or Berry (1993) must be used. Similar al- gorithms are also available in many statistical packages.