Friday, October 23, 2009

GRE physics

Over at Cosmic Variance, John Convey gives us a rare glimpse into the way the GRE exams are put together.

Firstly, there’s the format. The exam is 100 questions long, and you have 170 minutes to do it. This is, therefore, different from just about every other physics exam you have had in college, where you have, say, four to six problems in an hour-long exam. The GRE Physics problems (or “items” in assessment world jargon) are short, to-the-point questions, and just about all of them are short calculations, if any, and take little time once you see what to do. Writing such questions is a difficult thing to do, let me tell you. We are continually amazed how, after about six levels of review, we can find issues of clarity, reasoning, and even sometimes basic physics correctness in the items submitted to the pool. All the committee members spend a lot of time each year reviewing hundreds of problems, looking for flaws, but more often than you would think the face-to-face meeting in Princeton with the ETS folks reveals something previously overlooked. It’s a really interesting process.

For each new exam form we eventually arrive at 100 items that test mastery of a clear physics concept or idea, and there is, yes, a certain amount of memorization required in terms of the basic equations learned in undergraduate physics. But there are many problems that can be done using just concepts, and many that can be done with simple dimensional analysis. When there are numerical solutions (and many if not most are in that category) the numbers are chosen so as to allow easy arithmetic – no calculators are allowed.

He also offers quite a few tips for how to prepare for the GRE subject test in physics.

My first piece of advice to students studying for this exam is to focus on reviewing the textbook from your freshman introductory physics course. In my years on the GRE committee, when I have needed to consult a text, it is that text at least 80% of the time. If you master every example in there and review the basic equations, you will do really well on the GRE. I have found that only a small fraction of the items on the GRE are actually from upper-level topics like stat mech, quantum, and special topics (solid state, nuclear, particle, cosmology, etc.) And presumably you have been studying the advanced topics more recently anyway. I think the single biggest mistake students make in studying for the GRE is to focus on too-advanced subjects.

There's a lot in Conway's post. Go read all of it.