Null Hypothesis Watch

1. Pro:
Timothy Taylor writes,

Why do the academic effects of early childhood education so often fade out? Is it lack of lack of follow-up in schools? The importance of peer effects as student who received pre-K assistance are blended in later grades with those who do not? Maybe the pre-K programs themselves vary in some way?

Read the whole post. Not all of the evidence is consistent with the null hypothesis, but it is very difficult to reject.

2. Con: David Leonhardt writes,

“The gains to children in Massachusetts charters are enormous. They are larger than any I have seen in my career,” [education researcher Susan] Dynarski wrote. “To me, it is immoral to deny children a better education because charters don’t meet some voters’ ideal of what a public school should be. Children don’t live in the long term. They need us to deliver now.”

Pointer from Tyler Cowen. For this research to be convincing to me, it would have to show that there is not much fadeout and also that the interventions are scalable.

7 thoughts on “Null Hypothesis Watch

  1. The hardest point of education analysis is there is a huge self-selection bias in any study to disprove the null hypothesis. Living in California Riverside County, the kids schools test scores are significantly higher than they were 10 years when our community was mostly retiree and agriculture based. Now with more Middle Class families (FYI the market has turned around a lot and these schools are still mostly Hispanic-American), the schools test scores are above average now.

    1) Anyway I think Charter Schools are good idea to convince students that they can be kicked out at any moment.
    2) I think pre-K education is a great goal but has massive diminishing returns. (Which is really to hard to prove.) My kids benefited having 4 – 6 hours a week but anything more does nothing to improve children. (It might be the opposite that long hours in child care takes away quality time with parents.)
    3) The hardest thing about I see about Vouchers and Charters is somebody has to explain how education will work in the worst inner cities or the state of West Virgina. Using a grocery store analogy, why would private companies invest in poor markets?
    4) For all the complaints about education, graduation rates are at the highest point ever. So something is working right.

    • Co-workers once asked me a similar question as your #3. They couldn’t imagine how that would work.

      We happened to live work in a city known for it’s failing public school district. I pointed out to them that there are 20 charter schools already operating within the district and most are doing fine.

      They were unaware of that fact.

      So, explaining it should be as simple as pointing to examples where it is already working.

      Also, the charter schools are operated by various entities ranging from for-profit companies, neighborhood groups, local universities and not-for-profits.

  2. Kids learn a lot from each other, so it is possible the fade out is actually just diffusion, resulting in increases in all scores, but I don’t know if this was considered.

  3. It’s tough to do studies on charter school populations. For one thing, they can actually kick out trouble-makers and weed out kid-family combos who can’t manage the commitment. The option to fall back on the public system is completely asymmetric.

    • I remember a long time public school board member saying that charters were the best thing that ever happened to them. After charters started opening, and he had to deal with a difficult parent, he could always point out that if they didn’t like his response, they had a choice.

  4. Fadeout has long since been explained. All the folks who persist in failing to understand it suffer from ideological dyslexia and none of their hypotheses (nearly all of them tiresome variations on a few clichés) will ever beat the null hypothesis until they abandon their quasi-religious postulate that every young human is endowed with exactly the same mental propensities and abilities which develop on the same schedule “unless racism.”

    Fadeout has two chief causes.

    The first is the large heritable portion of intelligence. You can push children to pass cognitive developmental milestones a bit ahead of schedule, but that does not affect their final attainment much. Reams of solid research show that people end up (as adults) cognitively where their inborn talents predict (as children), with little regard to the intensity of their early schooling.

    The second is the somewhat different life trajectories of different races. Children (on average, of course) of sub-Saharan African ancestry grow more rapidly and mature earlier than those of European ancestry, who mature earlier than those of East Asian ancestry. Brains develop during childhood like other organs, so cognitive milestones are age-referenced. Earlier-maturing individuals respond well to early schooling, but education does not much affect the pace of maturation or the ultimate level of physical development, including brain development. Each child’s cognitive achievements at a given age are the (arithmetical) products of his or her maturation level, natural intelligence level, and intensity of schooling (the first is a fraction and the second a value which rises from zero to a personal maximum during childhood; for a given subject only the third can be varied by an experimenter). When you measure cognitive achievements of individuals against general-population norms, you can easily find that early schooling helps those who are maturing early to hit milestones like “learning to read” by a certain age without actually affecting their natural intelligence– or final educational attainment– at all.

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