Comparing an individual's test score against norms derived from small samples

The standard method for comparing an individual's test score with a normative sample involves converting the score to a z score and evaluating it using a table of the area under the normal curve. When the normative sample is small, a more appropriate method is to treat the individual as a sample of N = 1 and use a modified t test described by Sokal and Rohlf(1995). The use of this t test is illustrated with examples and its results compared to those from the standard procedure. It is suggested that the t test be used when the N of the normative sample is less than 50. Finally, a computer program that implements the modified t-test procedure is described. This program can be downloaded from the first author's website.