The Computation and Use of Residuals in the Analysis of Experimental Data

The use of a residual analysis prior to the performance of statistical tests upon experimental data is recommended as a routine procedure. This paper describes (a) the calculation of residuals from data resulting from a variety of experimental designs; (b) the “cleaning up” of the residuals to improve conformance to the assumptions underlying a subsequent statistical analysis, and (c) some methods of using the “cleaned up” residuals to detect various problems in the conduct of the experiment. An example demonstrating the computation and manipulation of residuals is given.