Evidence?

I have been thinking lately on the idea of evidence-based intervention. I say “the idea of” because that is all it really is at this point. An idea. I do not believe that professionals have come to an agreement on the definition of this concept. Some would say that an intervention is evidence-based if there is a statistically significant study published in a recognized journal juried by professional peers. Some would further argue that it would require such a study plus multiple successful replications. I go back to my roots as an Applied Behaviour Analyst and ask, what happened to our belief in the single subject design? Better yet, what if we were to base progress on a client’s baseline compared to treatment alone?
I ask these questions mainly because I am currently venturing into non-evidenced based territory … again.  I see possibilities. More to come.