The Null Hypothesis Strikes Again

Timothy Taylor looks at an OECD report on the effect of making a student repeat a grade. He quotes this sentence:

In practice, however, grade repetition has not shown clear benefits for the students who were held back or for school systems as a whole.

One interpretation of this is that the marginal benefit of an additional year of schooling is zero. However, that interpretation is not something that anyone wants to discuss.

And I could put the same headline on Tyler Cowen’s post about a study in France.

6 thoughts on “The Null Hypothesis Strikes Again

  1. Wow, so doing the exact same thing a second time doesn’t produce magically different results? How surprising! 😉

    • Hi Katie, I am sure that you do not mean that practicing the same thing over does lead to improvement, so what do you mean?

  2. More precisely, the marginal product of an additional year of schooling to the very worst students in the system is about zero.

    Catch a public school teacher in an unguarded moment, and they will agree to the proposition that removing the worst 10% or so of his/her students would improve outcomes for the 90% without materially harming the 10%. (That is, the bottom 10% get nothing from being there, and the disruption they cause harms the other 90%’s educational benefits.)

  3. It would be interesting to see repetition vs birth month. Perhaps this is mostly just timing of entry and starting age.

  4. People support holding kids back when they believe they can “catch up” when in fact, the held-back kids will be the low performers in the next class, as well .But accepting that “catching up” isn’t possible means accepting that our entire education policy is flawed, based on expecting equal results for all populations. Can’t have that.

    “Catch a public school teacher in an unguarded moment, ”

    No, teachers would not say that. They would agree that there’s no point to holding kids back, but they wouldn’t write off the bottom 10% as hopeless. Research shows, in fact, that the low performing kids do better when put with higher achieving kids.

    Now, catch teachers in an unguarded moment and they would say that the few percentage points of improvement the low-achieving kids see isn’t worth the strain of a huge ability range in a classroom, much less the big hit the top kids take in achievement from being forced to move more slowly. But that’s mostly in high school, when kids can’t “fail a grade”, and when the gap between what students can and can’t do gets huge. Anyone who thinks that moving kids faster through elementary school material makes a huge difference hasn’t been paying attention.

  5. @Rvman and educationrealist
    Not all who fail are the worst students in the long run. I failed the first grade twice and the second grade once. After 2 years in the first grade they did not hold me back again. I did eventually graduate from college though.

    In the 3rd grade they sat me next to the best student in the class. He became a life long friend. We shared a rental house in college and ironically I graduated and he did not. He was a smart guy but spent too much time watching TV. He did go back to school at about 35 years old and did graduate with a degree in economics.

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