“Ineffective treatments don’t cure an illness, so sufferers demonstrate them to more people than those who recovery quickly after taking real medicines.”
A mathematical evolutionary fitness model was used with variables for a treatment’s:
Rate of adoption and abandonment.
Effectiveness.
Odds of recovering naturally or dying.
Starting from one person demonstrating a treatment, either fake or real, it measures the rate of spread.
Fake things that people want to believe often cannot be absolutely disproved (particularly if they are placebos, like homeopathy or religious treatments such as praying), they spread better because treatments and evangelizing periods are longer since they do nothing, and people are not good at measuring success.
Situations where evidence is more likely to be persuasive, such as recurring diseases, tend to weed out quackery more naturally.
Clearly this has important implications for all sorts of areas from steak knife peddlers to management consultants and therapists.
If the model applies generally, for example, therapists would be more successful if fraudulent or bogus.