Simple Interventions that Work

by on May 14, 2011 at 10:14 am in Economics | Permalink

Sometimes simple interventions are the best. From research by Glewwe, Park and Zhao.

About 10% of primary school students in developing countries have poor vision, yet in virtually all of these countries very few children wear glasses….This paper presents results from the first year of a randomized trial in Western China that began in the summer of 2004. The trial involves over 19,000 students in 165 schools in two counties of Gansu province. The schools were randomly divided (at the township level) into 103 schools that received eyeglasses (for students in grades 4-6) and 62 schools that served as controls. The results from the first year indicate that, after one year, making eyeglasses available increased average test scores by 0.09 to 0.14 standard deviations (of the distribution of the test scores). For those students who accepted the glasses, average test scores increased by 0.12 to 0.22 standard deviations….

These are rather large effects; similar tests given to children in grades 5 and 6 in Gansu province show that an addition year of schooling leads to an increase of 0.4 to 0.5 standard deviations of the distribution of test scores, which implies that these impacts are equivalent to one fourth to one half of a year of schooling. Thus providing eyeglasses is a relatively low cost and easily implementable intervention that could improve the academic performance of a substantial proportion of primary (and secondary) school students in developing countries.

It’s interesting that many students/parents refused the glasses.

Hat tip to Stephen Dubner who has a good segment on this at Freakonomics Radio.

1 Helen May 14, 2011 at 11:00 am

One of the consequences is that flight/pilot schools have difficulty in enrolling students with good eyesight and good performance from high school.

2 RR May 14, 2011 at 12:17 pm

Are randomized trials really required to prove that glasses help children with poor eyesight in a number of ways , and one of them would be better performance in school ?

3 jmo May 14, 2011 at 12:31 pm

The question wasn’t really, “Does it help?”. The question was, “How much?”

If you were an NGO looking to find out where you’d get the biggest bang for your donor’s buck – this information is important.

4 david May 14, 2011 at 1:23 pm

What is it about East Asian school systems and glasses? It’s like myopia is contagious. The West has 15% myopia among school-going children, they have something like 85%.

I dimly recall that Taiwan, Singapore, etc. initially had trouble convincing parents to invest in glasses, too, back during the 70s? Perhaps there is a cultural barrier there.

5 RR May 14, 2011 at 1:50 pm

Probably a strong geentic component . From Wikipedia:
Myopia in China:
China has the highest myopia rate in the world: 400 million people are myopic out of its 1.3 billion people. The prevalence of myopia in high school in China is 77.3%, and in college is more than 80%.[68]

Ethnicity and race:
The prevalence of myopia has been reported as high as 70–90% in some Asian countries, 30–40% in Europe and the United States, and 10–20% in Africa.

6 doctorpat May 15, 2011 at 11:26 pm

The first thing that leaps to mind is that this correlates fairly well with how long it has been since people in those areas stopped needing to hunt for a living, and started digging at crops that were only arms length away.

7 mulp May 14, 2011 at 8:09 pm

I’m guessing david didn’t begin wearing glasses early in school.

I began wearing glasses when I was five or six almost 60 years ago. I was called names as a result. They became a big burden to me, and a significant expense to my parents. Seems like I broke them once a year or so, leading to a new round of doctor visits with eye drops, and struggling with broken glasses until the new ones were made.

Wearing glasses was “dictated by the government” schools, though that wasn’t the reason my parents sacrificed to pay for my glasses, both college grads/professionals.

And prescription glasses are in the West are still not cool or cheap or convenient. The “cool” glasses can’t be made for those like me who really need corrective lenses.

8 doctorpat May 15, 2011 at 11:23 pm

My glasses are cool.
Mum told me so.

9 rpl May 16, 2011 at 8:02 am

Children will find excuses to pick on kids they want to pick on, whether they wear glasses or not. They seize on whatever feature is notable and hammer away at it. I got glasses starting around age 7, and I can’t honestly say I got picked on more after getting them than before. The glasses were just one more thing to add into the rotation. As to the cost, I wasn’t privy to my parents’ finances, but they were solidly working class, and we still managed to make do.

I’m not sure what you consider “cool” glasses, but the last time I went in for a pair I had a wide range of styles to choose from and had no trouble finding one that suited me. With modern high-index materials even strong prescriptions do not have to be too thick, which greatly increases the options available (no great stagnation here!).

All of which goes to say that it’s pretty far-fetched to suggest that it is reasonable to sacrifice a child’s educational prospects merely to avoid the burden of wearing glasses.

10 Rahul May 14, 2011 at 3:07 pm

The refusal of eyeglasses by some is not that surprising. I grew up in urban India and the bullying, teasing and ridicule was substantial for the kids that had glasses in primary and middle school. I cringe just remembering all the derogatory epithets we had for them and the number of glasses we broke and bent in senseless pranks (and feel guilty of sort of participating in some of the bullying!)

By high school there were so many using glasses that bullying became pointless.

11 mulp May 14, 2011 at 8:50 pm

That isn’t unique to India based on my experience growing up in up state New York and several parts of Indiana…

12 Brandon Berg May 14, 2011 at 3:25 pm

Those numbers can’t be right, can they? If only 10% of students needed glasses, then how did making glasses available increase average test scores by nearly as much as it increased scores for the students who actually got the glasses?

13 Brandon Berg May 14, 2011 at 3:28 pm

Never mind. I just realized that the 10% figure was for all developing countries, whole the test was done in China, where the rate of myopia is much higher.

14 Ray Ban Eyeglasses June 9, 2011 at 3:19 am

This shows which they last very much lengthier and thus saving you income which could otherwise are actually utilized to purchase new ones.BJNVN

15 fischbone June 13, 2011 at 1:16 am

no ROI? (Return on Investment?) c’mon, guys, you’re doing yourself a disservice!

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