acroyear | "the plural of anecdote is anecdotes, not data"

Science-Based Medicine » The Role of Anecdotes in Science-Based Medicine:

The answer, as much as my question, exposed a core difference between scientific and sectarian health care providers. She said, “Because I have seen it work in my practice.”

There it is. She and many other practitioners of dubious modalities are compelled by anecdotal experience while I am not.

An anecdote is a story - in the context of medicine it often relates to an individual’s experience with their disease or symptoms and their efforts to treat it. People generally find anecdotes highly compelling, while scientists are deeply suspicious of anecdotes. We are fond of saying that the plural of anecdote is anecdotes, not data. Why is this?

Humans are social storytelling animals - we instinctively learn by the experience of others. My friend ate that plant with the bright red berries and then became very ill - lesson: don’t eat from that plant. This is a type of heuristic, a mental shortcut that humans evolved in order to make quick and mostly accurate judgments about their environment. From an evolutionary point of view it is probably statistically advantageous just to avoid the plant with the red berries rather than conduct blinded experiments to see if it really was the plant that made your friend sick.

Further, the most compelling stories are our own. When we believe we have experienced something directly, it is difficult to impossible to convince us otherwise. It’s just the way humans are hardwired.

Understanding the world through stories was a good strategy in the environment of our evolutionary history but is far too flawed to deal with the complex world we live in today. In fact, the discipline of science developed as a tool to go beyond the efficient but flawed techniques we evolved. Perhaps, for example, your friend became ill because of the raw eggs he consumed earlier in the day, and the plant had nothing to do with it. Evolutionary pressures favored a more simplistic approach to nature, one that tended to assume that apparent patterns were real.