Medicine without statistics is quackery; statistics without medicine is numerology. Perhaps
this is the main reason why clinicians should care about statistics.
Statistics in medicine began in the early nineteenth century (it was called “the numerical
method” then) and its debut involved disproving the most common and widely accepted
medical treatment for millennia: bleeding. From ancient Rome until 1900, all physicians –
from Galen to Avicenna to Benjamin Rush – strongly and clearly advocated bleeding as the
treatment for most medical illnesses. This was based on a theory, most clearly defined by
Galen: four humors in the body, if out of balance, led to disease; bleeding rebalanced the
humors.
Of course this was all wrong. Even the dullest physician today would know better. How
was it disproven?
Statistics.
Pierre Louis, the founder of the numerical method, counted 40 patients with pneumonia
treated with bleeding and showed that the more they were treated, the sooner they died.
Bleeding did not treat pneumonia, it worsened it (Louis, 1835).
Counting – that was the essence of the numerical method; and it remains the essence of
statistics. If you can count, you can understand statistics. And if you can’t (or won’t) count,
you should not treat patients.
Simply counting patients showed that the vaunted experience of the great medical
geniuses of the past was all for nought. And if Galen and Avicenna could be mistaken, so
can you.