Practicing School Consultants Can Empirically Validate Interventions: A Description and Demonstration of the Non-Concurrent Multiple-Baseline Design
School psychologists are committed to remedying student problems with procedures that are supported with theoretical and applied science (Hughes, 2000; Shapiro, 1996; Stoiber & Kratochwill, 2000). In addition to consuming research related to empirically supported interventions, some specific models of service delivery may allow school psychologists to contribute to this science with data collected during their professional practice. Behavioral consultation (BC) is a model for delivering science-supported interventions that requires the collection of within-subject, repeated measures data (Bergan, 1977; Bergan & Kratochwill, 1990). These data have applied value in that they can be used to evaluate intervention effects. However, because these data are often limited to baseline and intervention phase data (i.e., an empirical A-B design), there is little control for threats to internal validity (Barlow & Hersen, 1984). Thus, while the intervention may account for measured changes in behavior, it is also possible that other variables (i.e., uncontrolled threats to internal validity) account for recorded changes in student behavior. These uncontrolled threats to internal validity prevent one from establishing cause-and-effect relationships between interventions and behavior change. This limits the opportunities for practicing behavioral consultants to contribute to the scientific process of validating interventions (Hayes, 1985).