RANDOMIZED SINGLE-SUBJECT EXPERIMENTAL-DESIGNS

Books on single-subject methodology tend to focus on traditional opera nt research techniques and thus provide little or no discussion of ran dom introduction of treatments and statistical tests based on such ran domization, i.e. randomization tests. Those books are the principal re ferences to which researchers must turn for a comprehensive coverage o f single-subject methodology, and so many researchers are likely to be unaware of the relevance of randomization (random assignment of treat ment times to treatments) and randomization tests to single-subject ex perimentation. That is unfortunate because randomization is necessary in order to draw valid statistical inferences about treatment effects. The role of randomization in providing control over major threats to internal validity is explained in this article, and a number of random ized single-subject designs and their applications are provided. Appro priate rank tests are specified, and sources of free software for othe r, more complex, statistical tests are given. Copyright (C) 1996 Elsev ier Science Ltd