• “A set of logical constructs that jointly offer answers to the questions ‘why’ and ‘how,’ as in ‘why would someone change their behavior in this way?’ and ‘how could this behavior/situation/outcome be changed”[1]
  • A set of interrelated concepts, definitions and propositions that presents a systematic view of events or situations by specifying relations among variables in order to explain and predict the events or situations
  • A “dense[r]” and logically coherent set of relationships[2]
    • Provides views on causal relationships
    • Seeks to explain, predict and control phenomena


  1. Sales A, Smith J, Curran G, Kochevar L. Models, strategies, and tools. Theory in implementing evidence-based findings into health care practice. J Gen Intern Med. 2006 Feb;21 Suppl 2:S43-9.
  2. Kitson AL, Rycroft-Malone J, Harvey G, McCormack B, Seers K, Titchen A. Evaluating the successful implementation of evidence into practice using the PARIHS framework: theoretical and practical challenges. Implementation Science 2008, 3:1 (7 January 2008)