Arnold Kling  

Uncertainty and Bias

PRINT
Interview with Gregory Clark... DeLong is no Slouch...

Charles Lambdin writes,


Groopman’s position, when his various arguments are gathered and assembled, becomes untenable. He admits doctors suffer from innumerable biases that diminish the accuracy of diagnosis, reducing many diagnoses to idiosyncratic responses fueled by mood, whether the patient is liked or disliked, advertisements recently seen, etc. Thus Groopman agrees with decision scientists’ diagnosis of doctor decision making; but then he goes on to wantonly dismiss what many of the very same researchers claim is the best (and perhaps only) remedy, the way to “debias” diagnosis: evidence-based medicine and the use of decision aids. In place of statistics what does Groopman suggest doctors rely on? Clinical intuition of course, the very source of the cognitive biases he pays lip service to throughout his book.

...One study famously showed that a successful predictive instrument for acute ischemic heart disease (which reduced the false positive rate from 71% to 0) was, after its use in randomized trials, all but discarded by doctors (only 2.8% of the sample continued to use it).5 It is no secret many doctors despise evidence-based medicine. It is impersonal “cookbook medicine.” It is “dehumanizing,” treating people like statistics. Patients do not like it either. They think less of doctors’ abilities who rely on such aids.6

The problem is that it is usually in patients’ best interest to be treated like a “statistic.” Doctors cannot outperform mechanical diagnoses because their own diagnoses are inconsistent. An algorithm guarantees the same input results in the same output, and whether one likes this or not, this maximizes accuracy. If the exact same information results in variable and individual output, error will increase. However, the psychological baggage associated with the use of statistics in medicine (doctors’ pride and patients’ insistence on “certainty”) makes this a difficult issue to overcome.


It is better to be certainly wrong than statistically right. That is, doctors and patients feel better if the doctor makes a diagnosis based on intuition about the specific case rather than based on some statistical model.

In hindsight, it often appears that one could have made the right decision using better intuition. That is why an anecdotal approach to looking at medical decision-making is biased in favor of intuition and against statistical models. That same sort of bias is at work in the cries for more regulation of financial markets in wake of the subprime mortgage problems. In hindsight, you think that a regulator could have prevented the problem. But that is a biased perception.


Comments and Sharing






COMMENTS (6 to date)
Josh writes:
In hindsight, you think that a regulator could have prevented the problem

Oh man, if that doesn't explain about 90% of the laws we have today...

Floccina writes:

Josh writes:

In hindsight, you think that a regulator could have prevented the problem
Oh man, if that doesn't explain about 90% of the laws we have today...

I agree!
How about that very very silly report that came out yesterday about how the Virginia Tech shooting could have been avoided? What a hoot. If I was on the commity I would said just Stuff happens.

marianne writes:

Not everything is as clear as it might seem. It should be noted that there is a differentiated value for subprime or stated income loans in the commercial lending market. This loan type is not entirely bad despite the abuse of some in the residential lending arena. Oftentimes, individuals that want to start or acquire a small business, purchase a gas station, acquire a motel, open an auto repair shop or any of a myriad of sole proprietor establishements, and do not have the portfolio that would make them attractive to the big box leaders. Lending companies like Ocean Capital in Rhode Island offer subprime and stated income loans by using up close and personal evaluations of the borrower and the opportunity. We need companies like this to support new business opportunities.

Karl Smith writes:

One possible explanation for the love affair with intuition is that influential patients prefer intuition because they can influence it.

That is, a statistical model treats the grumpy homeless guy with the same methods and attention as the charming and handsome lawyer.

Perhaps, it is true that on average doctors perform worse than machines because on average doctors are treating the average person with an average level of attentiveness.

A particularly influential patient may be able to induce more cognitive work on the part of his physician and get an even better diagnosis.

Thus the influential patient prefers the status quo and the influential patient is well influential and the grumpy patient is not.

KSH writes:

It is this reasoning that makes me believe that Crisis of Abundance misses the mark.

The fundamental problem with medical care in the US is the legal enfranchisement of the AMA and the power of the doctor's guild. Open up medicine to any practitioner, and traditional Drs would be wiped off the face of the earth by those who used hard data not intuition.

bingo writes:

Ahhh, KSH, I fear that the practitioners who would wipe the doctors of today off the face of the earth would be the same type of "practitioners" who pre-dated today's doctors, the charlatans and predators who took advantage of the superstitions, fears, and ignorance of people in need of care. For better or worse, the AMA is nothing but a trade organization empowered to do little more than lobby on doctors' behalf and offer ethical standards of conduct that it is no longer able to enforce. There is no doctors' guild; in fact, doctors are considered indpendent businesses and are therefore forbidden to collude on any business matters by the Sherman Antitrust Act. Licencing laws for doctors, nurses, lawyers, beauticians and hairdressers, etc. have always been passed under the guise of "protecting the patient/customer" from insufficiently trained individuals who may cause harm.

After reading today's posts by Arnold et al. I reviewed the Preferred Practice Patterns for several major treatment categories on ophthalmology. In light of the article, book, and commentary what was extraordinary about the guidelines was how INEXACT they were. Some disease and treatment entities lend themselves very nicely to standardization and objective measurement (give a heart attack patient an aspirin within 30 minutes of arriving in the ER, stent the patient within 60 minutes and mortality is dramatically reduced). Others, like glaucoma, are only somewhat measureable (set a target eye pressure in each glaucoma patient) but defy any true metric that impacts outcome (there are NO standard target pressures that can be set based on standard exam parameters).

Medical conditions that lend themselves to simple, standard protocols may, indeed, lend themselves to treatment by non-licensed practioners (rapid-strep test positive strep throat = antibiotic), and indeed licensed doctors may lose this particular business to lower cost providors. Treatment to the mean and the mode is a reasonable goal since the deviation from each for many, many diseases is rather small (tight distribution curve). However, diseases have a tendency to come in clusters making a "clean" evidence-based intervention for a particular entity rather messy. Who do you want making decisions in THAT circumstance? Count me in for the doc with experience and intuition (whether I'm all dolled up and on the way to court, or a little messy, unshaven, and in need of a bath).

Comments for this entry have been closed
Return to top