Emily Oster tackles this question:
I generate new data on HIV incidence and prevalence in Africa based on inference from mortality rates. I use these data to relate economic activity (specifically, exports) to new HIV infections in Africa and argue there is a significant and large positive relationship between the two: a doubling of exports leads to as much as a quadrupling in new HIV infections. This relationship is consistent with a model of the epidemic in which truckers and other migrants have higher rates of risky behavior, and their numbers increase in periods with greater exports. I present evidence suggesting that the relationship between exports and HIV is causal and works, at least in part, through increased transit. The result has important policy implications, suggesting (for example) that there is significant value in prevention focused on these transit-oriented groups. I apply this result to study the case of Uganda, and argue that a decline in exports in the early 1990s in that country appears to explain between 30% and 60% of the decline in HIV infections. This suggests that the success of the Ugandan education campaign against HIV…has been overstated.
Since I used to believe Samuel Brittan when he argued that trade spreads sex, this result accords with my intuitions.
I thank Scott for the pointer. There should be an algorithm informing me every time there is a new Emily Oster paper. If Scott is indeed such an algorithm, I am pleased. And of course I am that algorithm for you.
“Since I used to believe Samuel Brittan when he argued that trade spreads sex, this result accords with my intuitions.”
What changed your mind on this?
Migrants are NOT exports and there are significant exports that do not involve people. This instrument has serious problems. Why not just connect migration and HIV? Better yet, how about people having sex and HIV? Oh wait.
that relationship is not causal.
It’s not exports or trade per se, it’s migration, especially seasonal migration.
Increase of export in ethiopian coffee doesnt increase migration as much as increase of export of copper in DRC and Zambia.
In South Africa, the case is even more complicated as migrant work was made larger by apartheid policies that prevented workers to permanently move (with their families and most importantly their wives) to the region where they worked.
I have a problem with any comparison of African AIDS to AIDS in the US and Europe. They are really 2 different diseases.
In Europe & US AIDs requires the presence of the HIV virus plus diagnosis of one of 28(or so) diseases. The one I can always remember offhand is tuberculosis. Thus, if you have TB AND HIV you have AIDS. If you have TB and no HIV you just have TB.
In Africa, they use the WHO definition of AIDs. This does not require testing for HIV. It looks only at symptoms including:
Weight loss
protracted asthenia
Continuous or repeated attacks of fever for more than a month
Diarrhoea lasting for more than a month
Other signs
Cough 2
Pneumopathy 2
Oropharyngeal candidiasis
And so on.
Absent a common definition of AIDs, lumping US incidences and African incidences is comparing apples and oranges and is a fool’s errand.
John Henry
Chronic or relapsing cutaneous herpes 4
Generalized pruritic dermatosis 4
Herpes zoster (relapsing) 4
Generalized adenopathy 2
Neurological signs 2
Generalized Kaposi’s sarcoma 12
The def is:
Since many diseases in Africa are spread by truck drivers who, bedding down for the night, often make use of local prostitutes, it could conceivably be argued that the trade that requires these trucks is also spreading the diseases. But it’s more accurate to say that ignorance and risky behaviour spreads disease.
Look, it’s an argument against trade that Tyler is willing to accept!
Shakespeare – one of the more interesting things in this article is Emily’s finding that the ABC campaign may be overstated in terms of its overall success. I’d be interested in reading more articles that carefully examine the impact of ABC, since the Bush Administration believes its efficacy to be very high. I also wonder if AIDS mortality might also be the cause of falls in AIDS incidence during the period where Uganda’s AIDS rates fell. Thomas Dee and Harrell Chesson have a 2003 article entitled “AIDS Mortality May Have Contributed to the Decline in Syphilis Rates in the United States in the 1990s” that finds the rapid fall in syphilis can be explained by the explosion of the AIDS epidemic here. They do not isolate the mechanism itself (AIDS mortality can cause syphilis to fall by killing individuals with syphilis, by making the sexual network less efficient, and/or through deterrence effects), but find nonetheless causality running in the direction of AIDS mortality on syphilis rates. Since Uganda had very high AIDS mortality, how much of the fall was due to simply the at-risk population becoming smaller? I’m not sure if Emily attempts to address that in her paper or not.
I think she also has to come up with AIDS mortality statistics by comparing death rates in various age groups across different countries that are either affected or not affected by AIDS.
Jason said:
John – in the US, AIDS is defined as the presence of an accompanying disease to HIV? So, it’d be possible to have a very high viral count and a very low T-cell but not have AIDS, or have a low viral count and a high T-cell plus one of the opportunistic infections and have AIDS?
It had been a while since I looked at the definitions. At one time, it was the presence of the 28(?) diseases PLUS HIV. If HIV was not present, it was not AIDS.
I just looked at the CDC def in Wikipedia and it has changed some from what I remember but still requires positively testing for HIV.
The WHO/Bangui def used in Africa now recommends but does not require testing for HIV. AIDS can be diagnosed in Africa based solely on external symptoms. These symptoms can also be caused by non-AIDS diseases.
John Henry
The forthcoming QJE correction that Hartford mentions in that article… Is it this correction? It does not appear that her main results are affected much by noting the incorrect transmission rates she’d been using.
Harford’s article is very light-handed, but he seems to be saying:
(1) There was an obvious data error in Oster’s paper that epidemiologists could very quickly spot
(2) Epidemiologists have considered and rejected her conclusion
As for (1), it doesn’t seem to be a very big deal in terms of changing her results (they still look almost exactly the same), but I imagine it’s a bit telling in that it reveals that no epidemiologist looked at her paper.
(2) is actually important, no?
LN – I saw that quote in the article. The error appears to be Oster’s use of two sets of transmission rates from other papers, right? But, the updated paper with the corrected data does not appear to change her results substantially. So then why does Hartford argue she shouldn’t be repeating her findings? Just because epidemiologists, in work before Oster’s work, had not find evidence for this effect?
As for (2). Hartford’s article notes that the QJE and Oster had provided earlier drafts to epidemiologists. I’m not sure if that means the QJE had it peer-reviewed by epidemiologists or not, but it does mention that effort was made to enter into public health and epidemiological community to get comments and discussion. Personally, in my experience, I’ve found a lot of turf mentality among the people in public health when economists begin working in that area. Or, just outright dismissal. Without more information about what Hartford is talking about, it’s hard for me to believe ex ante that Oster screwed up royally by hiding her work from the public health community, especially since Hartford indicates they had the work but never bothered to comment on it.
Plus, nothing that I’ve seen so far appears to justify Hartford’s dismissal of the paper. The corrections he notes don’t appear to undo the paper’s findings. And simply referencing two anonymous epidemiologists is just an fallacious appeal to authority without information on exactly what they did to investigate her findings. The chasm separating economics from other disciplines is partly methodological, partly ego, and while it is easy to blame the imperialist coming in, in my experience, I’ve seen close-mindedness and insecurities on the other end that contributes significantly to the lack of communication.
(I’m actualy amazed at the new transmission rates on a different note – M-to-F transmission rates that are slightly lower than F-to-M? I had no idea in Africa that that was the case, as under “normal” circumstances, the risk of infection is much higher for uninfected women matched with infected men than the other way around. Does this suggest that heterosexual coital practices in Africa increase the transmission rate of F-to-M? If so, what is so different that would make the transmission rate so much stronger for F-to-M?)
I was thinking of Oster’s claim that people in health had seen the paper. I doubt she’s lying about that. It could be referring to a conference where she presented the paper, as my recollection from speaking with Oster is that she ends up on a circuit that does put her around other people working in development, which is a diverse group of scientists and policy-makers. This point seems rather minor, especially in today’s environment where the Internet makes such work accessible.
The real point of Hartford’s skepticism is this QJE correction. But, as I said, I don’t understand how his skepticism is warranted by that correction. The correction doesn’t appear to be that big of a deal unless I’m missing something (or maybe Hartford is talking about something else).
As for your point that no one in history will bother to read her witchcraft paper because no one wants to interact with cranks. That pretty much sums up the arrogance and turf mentality I was talking about. Basically, they remain insulated from people outside their circle, and somehow that’s Oster’s fault? Your friend should consider writing a comment on that paper, in all seriousness. If it is such a badly written paper, then point out the problems and send the comment to JEP. Or send it to some journal in history. It’s one thing to say “I don’t believe the result” but it’s another to say “this paper has methodological flaws because data selection criteria bias the resutls in favor of Oster’s hypothesis.” The latter seems to merit a response. The former (which honestly is more of what I encounter when people object to economists working in this area – it’s more of an aesthetic response than a scientific one) does warrant a response.
Jason — I think you’re misreading Harford’s comment. I think he showed the paper to an epidemiologist, received a response of “no way this is right, we used to believe this but it’s been pretty thoroughly debunked, and by the way, I can tell you the author clearly made a data mistake here,” Harford checks with someone else and gets the same answer, he confers with Oster and basically gets confirmation (the most convincing evidence, she says, came out after her paper was published). He’s a bit bothered by the fact that she is still pushing her conclusions to Esquire, and writes a very soft piece on the whole thing in the FT talking about how we all need to talk more.
It’s a bit open to interpretation I admit but it seems pretty clear to me between the lines.
I think you’re seriously downplaying the epidemiologists here — Oster’s conclusion is apparently something they *wanted* to be true but have realized is false. It’s not that they’ve never heard of this idea before and can’t believe an economist outsmarted them.
My history friend sent a note to Harford upon seeing his article yesterday. If sufficiently encouraged she might write up a note, although it’s hard to see who will really care. Again, her reaction upon seeing the paper was “No historian took a look at this — it’s just too obvious.” Is it just because historians are arrogant snobs who turn their noses down on the poor disenfranchised economists? Maybe a little but let’s not pretend Emily Oster is not well connected. The witchcraft idea wound up in the New York Times *Year In Ideas* while she was an undergrad. She really couldn’t find anyone to take a close look?
Jason, it’s not that complicated:
But Oster’s conclusion is probably wrong. Epidemiologists embraced the idea of treating other sexually transmitted diseases a long time ago, but it has been discredited (to their deep disappointment) by a series of rigorous clinical trials. Oster says that the most convincing evidence came out after her paper was written; still, she has repeated her recommendations more recently in Esquire magazine.
Oster also made a mistake in handling her data.
Your interpretation does not fit what Harford is writing.
Why is Harford being so vague? To protect Oster or to smear her with innuendo?
We’ve looked at the data on Oster’s website of course. My friend might publish something if anyone is interested — but this would probably be the JEP, right? Again, I’m not sure any history journal cares.
I hear your comment on the “back it up” — I’ll just point out that *my* personal accusations of shoddiness in this thread are actually quite specific. Harford’s really aren’t, so I’m relying on the fact that he’s an economist with a FT column who has every reason to be sympathetic to Oster.
Jason,
True — I was a bit quick to jump into Oster in this case, probably because I was familiar with the witch trials paper. Harford really should explain.
Cheers.
LN: by the way, if either you or your friend want to email me, it’s “eoster@uchicago.edu”.
-Emily
I imagine that the four of us are the only ones reading now…
Let me just say that:
a) I said that Emily’s coding error, which indeed she did correct super-fast, “makes a modest but noticeable difference to her calculations”. I hope that’s fair.
b) The clinical evidence from several separate trials is that treating STIs in Africa does not help prevent the spread of AIDS; that’s much more important than any coding error. I know of this evidence only because three epidemiologists independently made the claim. It does not constitute an academic refutation, but I think it does constitute responsible journalism. All journalism, ultimately, is an appeal to authority: that’s how journalists work.
c) The title of my piece is not “Emily Oster is wrong”, and there is no “hate” in my article. I have a lot of respect for her work. Anyone reading the whole article – as Emily says, it isn’t very long – would see that it is about a broader point, that economists should try to discuss their work with other disciplines and that this is not always easy.
Kim,
I have thought about this, since as you point out the assumptions about time to death are an important input to the overall results. Obviously, the issue is that this type of data is difficult to come by. You need to know when people are infected, which is difficult to know even in the developed world. In Africa, the challenge is even more extreme. I had hoped for better information on this coming out of the medical literature, but was mostly frustrated.
I do attempt some robustness checks in Section 4.3 in the paper, including working with three different paths of time to death (including one with faster time to death). The export results hold up here, which I found encouraging. I am hoping with this paper I will get some feedback from epidimiologists, which may help guide this part in particular.
http://news.yahoo.com/s/nm/20071029/ts_nm/aids_usa_dc;_ylt=AntIANW4Gkag8IhAD8K249pg.3QA
I’m suprized about size of the correlation, but not the relationship.
There’s a cultural aspect, I remember reading that there is a saying in some African country. It is something along the line of “It is impolite to return home from a trip early, you will interupt your wife and her lover.”
Despite the horrific opression and abuse of women in some culture, women have a lot of power in many. It’s understood that the wife will have affairs when the husband is away. This is a major factor in the spread of HIV because women are more susceptable to reception of HIV and because the viral load is very high in the first two weeks of transmission. That means that there is a greater likelihood that the male partners will also be infected. Concurrent relationships significantly increase the rate of spread. The amount of overlap is more important than the number of partners.
Is the relationship strongest for exporters vs importers?
Emily,
Excellent work, and insightful presentation. I read the entire page of comments and absorbed as much as I could about this controversy. While I can’t say that I understand the fine points of it, I know that strong minds inspire strong questions/opinions/attitudes in themselves and others.
If I may humbly offer something to you and the discussers:
I work as a professional teacher and tutor. It’s a modest job: the “value” of interacting with children, in stark economic terms, is not high in our culture. And we’ve all had bad teachers, those who shouldn’t have been doing what they did.
But I am proud of what I do, and am very good at it. My chief skill, as a teacher, is this: I can quickly read how other people react to new information.
1) I read body language quite well.
2) I can sense emotion behind words, more easily with handwriting, but even with typed text, based on the immediacy with which the reader addresses questions sent to him.
I’m going to put those two skills into use right now. I hope it inspires something.
Emily, while watching your presentation I found it difficult to follow what you were saying. Whether you made this choice consciously or not, it seems that you were more concerned about conveying information quickly than the receptivity of your audience. You spoke rather quickly, and didn’t insert pauses or light-hearted fodder that allows the audience to catch its breath and process.
I bring this up constructively, because I could sense from the discussion board that some people were reluctant to admit economic findings (one person said it reduces human behavior to “vector algebra”). I think this criticism, for most people, was emotionally triggered. Any good teacher knows that at the point that students get emotionally triggered, they can’t learn the material.
This means that for your insights to receive the intellectual praise and unbiased discussion they deserve, the presentation of your information needs to be… well, more emotional, more sociable, and more culturally attuned… the very things that economic analysis tries to discount in favor of more quantifiable, measurable data.
Learners look at the whole picture–emotional, physical, and mental.
In other words, your analysis can ostensibly discount the importance of emotional, social, and cultural factors as you did in your presentation–and there is HIGH value in doing so, because it helps us get clearer in our thinking–but if you’re going to do that, you have to embody the very things you omit. Otherwise most people will get a sour taste in their mouths, and miss out on some truly stunning findings.
Humanize the presentation of economics, so that you can economize the living of humanity.
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