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Evidence-Based Practice: Four Levels Revisited

In 2003, I wrote an article for Healthcare Design magazine titled “The Four Levels of EvidenceBased Practice.” It began by saying evidencebased design (EBD) is a parallel or analogue to evidence-based medicine and described it as “the deliberate attempt to base design decisions on the best available research evidence” (Hamilton, 2003, p. 19). The article has been popular and frequently cited. Most of it is still good advice; some issues, however, were not addressed or fully explained. After nearly 2 decades, it is time to follow up with reminders of what was in the original and additional thoughts that improve the understanding of the concept. Level 1: The article described Level 1 practitioners as those who believed in the concept of improving design decisions by reference to available evidence and who made an effort to stay current with the field’s literature. These designers make critical interpretation of the implications of the research for their specific projects and adopt EBD concepts. Once the project is completed, these practitioners seek out success stories that support their design choices. The weakness of Level 1 is the failure to seek both positive and negative feedback, upon which to act in a process improvement model. At the time, I did not address the difficulty practitioners might have in gaining access to credible research, which has continued to be a major problem. Level 2: The next level assumes all the features of Level 1, while adding another dimension. It assumes a belief in the concept of improved design decisions influenced by evidence, currency with the literature, and the expectation of including EBD concepts in projects as described for the first level. The practitioner at Level 2 must now hypothesize the expected outcome associated with the evidence-based concept, developed by interpreting the implications of research, and commit to measuring the results. For those who feel that predicting an outcome associated with a design concept is not science, try calling it a design hypothesis. You must, however, make a prediction about your work and make measurements.