Paul R. Yarnold
Optimal Data Analysis, LLC
Classic research tested the a priori hypothesis that fear and specificity of recommendation synergistically influence a person’s decision to have a tetanus inoculation. Data were inappropriate for analysis by one-way chi-square, and results obtained using chi-square missed the hypothesized interaction: “…specific plans for action influence behavior while level of fear does not” (p. 27). In contrast, for this design CTA identified a relatively strong, statistically reliable, and cross-generalizable two-strata model that supported the hypothesized interaction. The underlying design was then restructured as a 2 (Fear) x 2 (Recommendation) between-subjects factorial. Data for this design were also inappropriate for analysis by chi-square, but CTA found a relatively strong, statistically reliable, reproducible three-strata model that supported the hypothesis.