Analyzing single-case data with visually guided randomization tests

The valid use of a randomization test with single-case data typically involves the choice of a test statistic prior to gathering data. In situations in which it is difficult to anticipate the form of the effect, the early specification of the test statistic can be problematic. The purpose of this paper is to demonstrate methods that will allow single-case researchers to conduct valid randomization tests in situations in which they wish to delay the specification of the test statistic until the data have been observed. A concrete example is given to motivate the use, explicate the logic, and demonstrate the conduct of this method.