“Perhaps It Would Be Better Not to Know Everything”1

The advent of statistical methods for evaluating the data of individual-subject designs invites a comparison of the usual research tactics of the group-design paradigm and the individual-subject-design paradigm. That comparison can hinge on the concept of assigning probabilities of Type 1 and Type 2 errors. Individual-subject designs are usually interpreted with implicit, very low probabilities of Type 1 errors, and correspondingly high probabilities of Type 1 errors, and correspondingly high probabilities of Type 2 errors. Group designs are usually interpreted with explicit, moderately low probabilities of Type 1 errors, and therefore with not such high probabilities of Type 2 errors as in the other paradigm. This difference may seem to be a minor one, considered in terms of centiles on a probability scale. However, when it is interpreted in terms of the substantive kinds of results likely to be produced by each paradigm, it appears that the individual-subject-design paradigm is more likely to contribute to the development of a technology of behavior, and it is suggested that this orientation should not be abandoned.