Michael Shermer coined the term “folk numeracy” to describe human’s “natural tendency to misperceive and miscalculate probabilities, to think anecdotally instead of statistically, and to focus on and remember short-term trends and small-number runs.”
Our thinking is prone to focus on that hot streak we had in blackjack, all those Patriots games won when a lucky t-shirt was worn and ignore the larger trends and the many times the outcome was different. Our intuitive sense of tendencies and statistics is just not that good.
This idea of folk numeracy has a few applications to physical therapy practice, particularly the observed successes of our interventions. As mentioned before, we are prone to over extrapolating those handful of times where we had some sort of astonishing success while the numerous times where our treatments did not do much of anything fade from memory. The end result is that we are mostly no good at judging the anecdotal effectiveness of things like physical modalities, education, cabbage, or any other intervention. This shortcoming is compounded by the effects of things like confirmation bias and survivorship bias.
Folk numeracy is a good example of why we need a scientific approach in physical therapy and skepticism in our thinking. This is because science is a way of limiting our propensity to misjudge probabilities and statistics. Data is collected in a controlled fashion, analyzed carefully and the risk of bias is minimized. The error of interpretation is still there, of course, but it is more reliable than our personal recall and observation. Science then allows us to make better informed judgments about our efficacy and effectiveness and deliver better care to patients. Without it we are just guessing, and probably getting it wrong.
Photo courtesy of the fantastic Coen Brother's film, A Serious Man (2009). Go watch it.