“Study the High yield stuff”. “Don’t bother with that because it’s low yield”. When I was just starting my review, these are the most common advice I get from “experts” in forums and books about reviewing for the USMLE. The question is how good is this advice. If you are just aiming to pass the exam or get average scores, it is very good advice, but if you are aiming to ace the exam then watch out as it could bite you.
First, we must understand that Medicine, whether Basic or Clinical Science is a very vast field with many important concepts necessary for its practice. It is so vast that medical specialties arose because it is impossible for any one person to know everything. However, the USMLE has to be able to assess if you know enough about Medicine in 350 q’s or so per Step. Therefore, certain concepts will be more commonly tested than others will and high yield concepts will be tested more often than low yield ones.
However, although a high yield concept will appear more often, it is not 100%. On the other hand, many low yield concepts will probably not appear in the exam but again it is not 0%.
To illustrate, for example, say for Step 1 there are 3000 medical concepts that can appear in the exam. (The USMLE has a list of topics that can be tested in the exam) Let’s say about 200 concepts can be considered high yield, 400 concepts medium yield and 2400 concepts low yield. (These are not actual figures, just used for easier illustration and dividing concepts into high, medium and low yield is arbitrary but again needed for illustration purposes)
Out of the 350 q’s in step 1, let’s say around 140 will consist of high yield questions. Therefore, 140 of the 200 high yield concepts will appear in the exam giving each concept of a 70% chance of the question appearing in the exam. Now the next 100 questions will feature the 400 medium yield concepts giving a 25% chance of that concept appearing in the exam. If it takes an hour ( a day, a week or a month, whatever) for you to study 200 concepts, it is better to spend that hour learning high yield stuff as you can get 140 q’s correct, while studying medium yield stuff for the same time interval will get you only 50q’s (100 concepts divided by 2). And so it goes down the line.
Therefore, it does make sense to study high yield stuff. And if you just want to pass or get an average score, this is the best approach. Remember not all high yield stuff will appear in a specific set of exam. However, for any large group of examinees, all the high yield stuff will eventually appear in the exam. On the other hand, low yield topics will not appear all the time, but some of them will show up in the individual examinations. If you want to score high, you not only have to know all the high yield stuff, but every low yield stuff you know will be crucial to scoring high.
Further example. In Step 1, anatomy is considered low yield stuff. Why? Because although the subject is vast with lots of information to memorize, probably only 15 to 20 questions will appear in the exam, making it low yield. But 15 to 20 questions still count to your score and it may mean the difference between a mid 90’s vs. 99 or even low 99 vs. high 99.
Of course, it does not make sense to fill your head with low yield concepts at the expense of high yield stuff. There is a danger of failing the exam altogether if you do this. If you lack time for review, or have a poor memory, you should stick to high yield stuff. But if you have time and good memory and really want to score high, then go for the low yield concepts too, so long as you make sure it is not at the expense of remembering the high yield concepts.
Most reviewers contain only high yield stuff, therefore is ideal for people who only want to pass or get average scores. Textbooks have both high yield and low yield stuff, but also too much low yield stuff that won’t ever appear in the exam. Remember, USMLE will have to come up with questions even for low-yield stuff and therefore it does not have an endless pool of questions. Some concepts will be too obscure or specialized to ever be tested in the USMLE. There are very few reviewers that contain not only High yield stuff but enough low yield material that it is possible to use them to ace the exam. Usually the only way to ace the exam is to occasionally go to textbooks or for pathology, listen to Goljan’s lectures.
Now one of the reasons USMLE World Qbanks are more difficult than Kaplan’s (though not the only reason) is because UW tends to test more low yield concepts, correctly guessing that most people have reviewed the high yield stuff already and need to be drilled more on the low yield stuff to score high. I will talk on the difference between UW Qbanks and Kaplan Qbanks in another post.
So in conclusion, if you just want to pass the exam or get average scores, stick to high yield concepts. If you want to ace the exam, learn as many low yield concepts as you can without sacrificing high yield concepts. Even among low yield concepts there are some more high yield than others. Example, brachial plexus in anatomy. If you have limited time, or you know you just can’t remember that much, then stick to high yield concepts, better to pass or get average scores than to fail.