The power of anecdotes…

Trump & Cuomo have jumped aboard the Hydroxychloroquine train, spurred on by pop-docs like Dr. Oz.

Dr. Fauci is “hesitant” because there haven’t been scientifically-pure randomized controlled clinical studies …  just “anecdotal evidence”.

Memo to Dr. Fauci: Don’t underestimate the “power of anecdotes” in shaping decision-making and public opinion.


In my Business Analytics course, I had students read a couple of excerpts from a book called Think Twice: The Power of Counter-intuition by Michael Mauboussin.

In a chapter called “The Outside View” the author reports findings from a medical study that investigated the relative importance of hard data and anecdotal evidence when patients select from among treatment options for serious health conditions.

Patients were given the hard scientific data about a treatment‘s success rates and an anecdote about a case history.

Some anecdotes were positive (the treatment was a success), some were negative (the treatment failed or had complications), and some were neutral (neither a clear success nor a dramatic failure).

Below is an extract of the study’s results summarizing the percentage of respondents selecting a treatment given the hard data on its success rate and a related anecdote of a specific case’s outcome.


Let’s drill down …


When a  treatment with a high success rate was paired with a positive case study, it won hands down.

Similarly, when a treatment with a low success rate was paired with a negative case study, it lost by a mile.

So, good so far.

But, when when a treatment with a low success rate was paired with a positive case study it was selected at about the same rate as a treatment with a high proven success rate.

Said differently, a positive case study (i.e. anecdote) – even if it was an unlikely outlier – had the power to swamp the hard scientific data.

So, when there is no hard scientific evidence to the contrary … the anecdote prevails.


Let’s apply that finding to the Hydroxychloroquine debate.

Clinical trials are done to evaluate two factors: safety and efficacy.

Hydroxychloroquine has been safely used for decades — primarily to combat malaria … but extended to lupus and rheumatoid arthritis.

Of course, there may adverse effects with COVID patients — especially those with multiple co-morbidity factors … but, the medical consensus seems to be that safety is not an issue.

What about efficacy?  Does it work?

Hard evidence is sparse.

There is the French study on 40 CODID patients.

The results were compelling: the virus was eradicated in all patients with no detrimental safety issues.

But — Dr. Fauci says — the numbers are small and there wasn’t a random control group for efficacy comparisons.

My view: so what?

And now, there are heart-wrenching video clips of patients who were pulled back from the brink of death with Hydroxychloroquine.

Anecdotal? Yes.

Projectible? Nope.

Opinion-swaying? You bet.


P.S. I think that a good, pragmatic compromise was reached when the FDA cleared Hydroxychloroquine for doctor-controlled off-label use of Hydroxychloroquine on NY’s COVID cases.

If there are safety issues, they’ll show up quickly.  If patients are cured, who cares if it’s attributable to Hydroxychloroquine or simply a placebo effect?

Follow on Twitter @KenHoma

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One Response to “The power of anecdotes…”

  1. Would I take HCQ like Trump is doing? | The Homa Files Says:

    […] The power of anecdotes  […]

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