Dear Economist,
My economics tutor says that I should be studying harder if I want to do well in my exams. I think that he is basing his advice on purely theoretical assumptions, and that there is no empirical evidence for his assertion. Who is right?
M.W., Cambridge

Dear M.W.,

You’re probably correct that his advice is not based on empirical research – not because no research exists, but because it is very recent. But I am sorry to report that his wild speculations have now been confirmed by an intriguing natural experiment.

Previous researchers have struggled to establish a causal link between exam results and time spent studying. That is not a surprise. Bright students might work harder because they enjoy the work. Or failing students might cram to rescue their grades. Untangling the statistics seems impossible.

Yet the puzzle has been resolved by Todd Stinebrickner, an economist, and his father, mathematician Ralph Stinebrickner. Equipped with detailed time-use questionnaires, they looked at students who were randomly assigned a room-mate with a games console. Neither the students nor their room-mates differed in, say, initial test score, time spent boozing, or sleeping. But students whose room-mates had video games spent less time studying and more playing Final Fantasy XII. Pure chance – the assignment of a room-mate – seems to affect time spent studying, and no other important decisions. And yes, the grades did suffer.

If the analysis is correct, an extra hour a day studying has a very substantial impact on test scores – enough to lift a typical student into the top third. Unless you know some very good computer games, that is likely to be a rational investment of your time.

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