
A review of the effects of installing air filters in classrooms - thatcat
https://statmodeling.stat.columbia.edu/2020/01/09/no-i-dont-think-that-this-study-offers-good-evidence-that-installing-air-filters-in-classrooms-has-surprisingly-large-educational-benefits/
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dang
A thread on the article that Gelman is responding to:
[https://news.ycombinator.com/item?id=22006033](https://news.ycombinator.com/item?id=22006033)

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hanoz
> _When you see a report of an interesting study, contact the authors and push
> them with hard questions: not just “Can you elaborate on the importance of
> this result?” but also “How might this result be criticized?”, “What’s the
> shakiest thing you’re claiming?”, “Who are the people who won’t be convinced
> by this paper?”, etc._

That's a nice set questions, unnervingly disarming! Versatile too - it would
be interesting to see some journalists use a similar line of enquiry with
pronouncers of political policy.

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virtuous_signal
The sad fact is that sober analyses like these won't make their way around.
Meaning a large subset of readers of the first article will have more
"evidence" for their mistaken interventions to improve academic performance.
On the plus side, installing air filters in schools is cheap enough that they
should do it anyway -- not to mention the morality of forcing kids to be in
school for half the day when the conditions aren't healthy.

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boxcarr
It's obvious. The author of the air filter paper didn't have the luxury of
having air filters in their office. They're hardly to blame.

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masonic
I thought a current suspect of diminished classroom performance is _CO2_ , and
a typical filter won't help there. I'd like to see a study with CO2
sequestration in classrooms and/or other people-dense indoor settings.

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DoingIsLearning
> CO2 sequestration

Or perhaps design buildings with windows that people can open?

At the risk of sounding facetious, I think most people underestimate how much
CO2 is produced by 20 odd people in a room. Equally we underestimate how much
air is renewed by just opening a window.

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cjlars
I really wish this was a continuing series on research that gets picked up in
the popular media. There's so much questionable coverage out there.

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atheriel
That is in fact a common topic on Gelman's blog, if you go through the (large)
archive.

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gfody
..or schools willing to change their air filters (or attempt to measure the
effect of having changed their air filters) are more likely to be among the
higher performers according to traditional KPIs (when controlled for observer
bias)?

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Someone1234
The article explains why the air filters were installed, and it doesn't fit
your supposition.

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gfody
agree, I actually expect there to be all sorts of positive correlations with
clean air - but they all start with caring about it enough to do something
like change a filter

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lalaland1125
gfody, the schools had no choice about changing their filter or not. In fact,
the whole premise of the study relies upon that fact!

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gfody
good point, crucial even.. thank you I should get back to work :)

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keanzu
_New study finds no evidence of educational benefits from installing air
filters in classrooms_

A new study was performed of a set of Los Angeles schools and found no effects
on test scores, comparing schools with and without newly-installed air
filters.

However, this was a small study, and even though it found null effects, it
could still be worth exploring the idea of installing air filters in
classrooms, given all that we believe about the bad effects of air pollution.

We should not let this particular null study deter us from continuing to
explore this possibility.

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datashow
If the air pollution is really a problem, shouldn't the locals address this
problem for the sake of public health?

This is something I don't understand. Is it possible that the air pollution
doesn't create health problem, but only creates cognitive problem?

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koksik202
There was article here not so long ago linking how pollution affects IQ so I
am more and more convinced that in the times where air is polluted by smoke
and microplastics there can be a benefit of installing filters, if it is
something that costs 600 dollars per classroom to fit two Dyson air filters it
makes sense to spend this kind of money even to ease breathing for kids with
Asthma

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feistypharit
I can't figure out what kind of common air filter would filter out natural
gas?! Am I won't out would they have never worked for their intended purpose?

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feistypharit
Damn auto correct. "Am I wrong or"..

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sp332
You should still be able to edit your comment. There's a two-hour window.

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vecter
Thanks for posting this. The tl;dr is:

> I don’t think the correct summary of the above study is: “A large effect was
> found. But this was a small study, it’s preliminary data, so let’s gather
> more information.” Rather, I think a better summary is: “The data showed no
> effect. A particular statistical analysis of these data seemed to show a
> large effect, but that was a mistake. Perhaps it’s still worth studying the
> problem because of other things we know about air pollution, in which case
> this particular study is irrelevant to the discussion.”

> The point is that these data, analyzed appropriately, do not show any clear
> effect. So if it’s a good idea to keep on with this, it’s in spite of, not
> because of these results.

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scottlocklin
Better than the other article by far.

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tschellenbach
Anyone with expertise in this field care to comment? It seems too good to be
true?

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bsder
Another problem that is becoming more of an issue recently is that the "energy
efficient sealing" of rooms is causing carbon dioxide to rise higher than
expected. Installing air filters may be a proxy for mixing carbon dioxide
better with outside air. <shrug>

In short, this study has no real controls, a lot of problems, and not a lot of
evidence.

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jaclaz
As a side note, it is not like the kids live in the classroom, they are
exposed nonetheless - when outside the classroom - to "normal" air, let's say
that in a week they are 30 hours or less in class and the remaining 138 hours
they are not.

So these magical filtering allows for intellectual improvements when impacting
roughly 30/168=17.8% less than 20% of inhaled air?

