Friday, January 14, 2011

Another tool to help medical students decide on a career

A quick recap of medical education before I get into the item of discussion. The traditional sequence of educational events for foctors in the U.S. if to first complete a bachelor's degree (at a minimum). This is most commonly done in a scientfic field such as Biology, Chemistry, Microbiology, etc. Two notes are that 1) for the most part, there is not really a "pre-med" major, you have to get your degree in some field and 2) more and more people are going to medical school with degrees in humanties and social sciences which medical schools are interested in matriculating to enhance diversity of the student body.

After this comes four years of medical school. The first two held in lectures/classrooms with a courseload somewhere around 30 credit hours per semester (yes...). Third year is in clerkships experiencing what different specialities of medicine are like. The fourth year is a mishmash of elective, required additional training, interviewing for residencies, and a little bit of goofing off with your classmates.

Many future doctors decide on a specialty sometime during their third year. Some know from the time they start (ie: Mom/Dad did such-and-such and I want to do that too). Some struggle and change their minds frequently, even up until the last minute and might even interview for multiple specialties.

R Scott McCain et al have published in the British Medical Journal, a new strategy for answering this crucial question. They observed all the doctors at their hospital as they were arriving for the morning and parking their cars. The researchers watched to see how many doctors had their parking-deck swipe cards out and ready when then pulled up to the gate and then how long it took them to park and exit the lot. They knew the identity of each doctor and then analyzed the data based on gender and their specialty of medicine.

The results? No differences in gender, men and women parked in the same amount of time, on average. There were differences by specialty, however. Surgeons parked the fastest and internists parked the slowest. The authors postulate that medical students should therefore be monitored on arrival to school and directed towards different medical specialties based on the time it takes them to park.

Sound preposterous? Well, it clearly is. This research was published in the BMJ's Christmas issue, in which they traditionally include some piece of tongue-in-cheek "research" which is good for a laugh. I wanted to present it because I enjoyed it and thought it was funny, but also to illustrate an important point, which is that people who do not know any better frequently make such logical errors and use "statistically significant" findings to justify whatever they want to prove.

In this case, the study is a cross-sectional study. It takes a single measurement of some outcome across several groups and demonstrates a difference between the groups. The study's design does NOT make any measurements over time to be able to predict anything about future performance in parking. Even more absurd then is the author's conclusion that a person's parking time could possibly predict the type of medicine they would go to practice. That would require a completely different study design. Lastly, to actually test their proposed conclusion that parking times could predict future medical specialty, you would need to perform a randomized trial and either let people pick their own specialty (control group) or use their time to select for them (experimental group) and then measure some outcome of whether of not you were right (physician happiness?) years later.

These realities are a big part of why people promoting junk science use shortcuts. Randomized trials are hard and take time and resources. Cross-sectional studies are easy and fast, heck, you can just send an undergrad to a parking lot and gather enough data to generate "significant" results. If you can then fool people with those data, why bother gathering the high quality stuff?

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