Thesis advisor: Lauren Saenz / Methods for classifying and treating an outcome variable are critical to explore in health research and evaluation, given the potential impact the choice of method may have on the findings and subsequent recommendations (Merbitz, Morris, & Grip, 1989). Further, given the prominent application of the Transtheoretical Model in health research, the stages of change construct continues to be a critical outcome measure concept used in various applied evaluation studies (Bridle et al., 2005; Nigg, 2002; Prochaska, DiClemente, & Norcross, 1992). The purpose of this dissertation study was to determine if findings differ depending on the approach to categorizing and analyzing a stage of change outcome variable, and if so, to highlight how these may affect policy and programmatic decision-making. Using data from a study on evidence-based program adoption decisions, this dissertation examined five approaches to treating and analyzing a single Decision to Adopt outcome variable. These different approaches were compared from both a methodological and pragmatic perspective. Hypothetical stakeholder illustrations were used to highlight differences in decision-making priorities and use of findings based on role, background, and organizational priorities. In comparing methods for classifying and treating the stage of change outcome variable, findings revealed notable differences in effect size, estimation, implication of major findings, and limitations of approach. The hypothetical stakeholder illustrations stressed the significance of personal values and preferences as key influential factors in decision-making and use of evaluation results. This dissertation highlighted how decisions are inextricably linked to the logic model and underlying theory, particularly as it relates to defining evaluation questions, determining how to categorize constructs, and assigning value to codes. Further, it reinforces the significance of contextual considerations in evaluation and how these cannot be ignored in the decision-making process (e.g., budgetary limitations, practical constraints, political factors). The proposed directions for future research seek to continue advancing this understanding of the impact of methodological decisions in different contexts and help improve the utility of evaluations more broadly. / Thesis (PhD) — Boston College, 2014. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Research, Measurement and Evaluation.