Cognitive ability tests are the best way for medical schools to select their entrants

Apr 11 2008

Cognitive ability tests are the best way for medical schools to select their entrants, rather than interviews and psychological tests, says an editorial in this week's BMJ.

The selection of tomorrow's doctors is an issue of enduring interest because it raises questions about predicting the characteristics of a good doctor, write Celia Brown and Richard Lilford from the University of Birmingham.

Society pays around £200,000 to train each medical student, but the cost of getting it wrong is much greater.

According to the authors, doctors should have three broad attributes—cognitive ability, humanity, and diligence. While it would be desirable to screen potential doctors for all these attributes, the evidence suggests that only cognitive ability can be assessed with reasonable accuracy in the context of mass selection.

School examination results have been shown to predict academic performance at medical school, but some argue that British A-Levels are not helpful for selecting medical students because most candidates applying for medical school achieve the top grades and they favour students from more privileged backgrounds.

The authors suggest that these criticisms could be rectified by basing selection on actual marks awarded rather than on course grades and adjusting entry requirements according to the applicant's background.

Despite these solutions, say the authors, some medical schools have introduced ‘aptitude' tests that do not appear to predict clinical performance, casting considerable doubt on their value as predictors of performance beyond medical school. They are also costly for both candidates and universities and there is no evidence that selection based on such tests results in improved prediction compared to the use of school examination marks alone.

In addition, psychological tests and tests to measure ‘empathy' are not adequate for selection, claim the authors, as we simply do not know the mixture of traits that are favourable for both diligent service and personal progression. And, unlike IQ or examination results, they can be manipulated to provide socially desirable answers.

Interviews also have a low predictive accuracy, they add. They often let through the people they are supposed to eliminate and appear to be biased towards people with a pleasing appearance.

The authors therefore suggest that tests of cognitive ability are the best way to select medical students because the processes they test are similar to those used in clinical practice—the application of knowledge to a problem.

Many European countries use a lottery, weighted by school-leaving examination results. Such a random process, while not the authors' preferred option, at least avoids the illusion of scientific probity, they conclude.