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Things you know about AIDS

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Patrick:

--- Quote from: pilsner on 21 Mar 2008, 09:07 ---Borders in sub-Saharan Africa aren't like borders in the West. (snip) Every time there's a major upheaval, hundreds of thousands cross borders en masse seeking to escape violence.  Tight border controls for many of these countries are about as realistic as magic HIV curing pixie dust.

--- End quote ---

Idunno, there was that Peace Corps volunteer a couple months ago who tried to evacuate Kenya's election-related violence by hiding in a potato truck, and they got stopped at the border and all of them got turned back because she was unable to get her passport from the Peace Corps office, because, well, the capital was kindof going through a lot of urban warfare.

To be fair she was white and stood out like a goddamn neon sign in the heart of Africa, but the point is that some countries are finally able to control their borders more effectively. On the other hand, though, some countries don't want to control the borders, because the governments themselves are involved in illegal trafficking.

dennis:

--- Quote from: pilsner on 24 Mar 2008, 14:14 ---No, at 14:30 of the talk Oster states that the ABC campaign may have been 25-50% less effective than previously thought, ergo the 15 billion dollars in aid might be better spent other than on an education campaign.  She never suggests that the ABC campaign was ineffective, just less effective than previously thought.  Keeping in mind that, according to Oster, Uganda's infected rate dropped from 19% to 6%, this is a significant distinction.  In any event, my point remains that even if we give Oster the benefit of the doubt and assume that only half of the 13% drop in infected is due to ABC, the impact of this analysis is lessened by the dependence of an education campaign on the culture in which its being implemented.
--- End quote ---
Well, we agree that Oster is trying to show that the effectiveness of the ABC campaign is overstated. The cultural dynamics of an ABC campaign is out of the scope of her talk.


--- Quote ---I'm sure Oster's regression analysis came up positive.  I'm also sure that you're aware how unreliable regression analyses are.  You ever hear the old adage about two economists and three opinions?  In any event, I'm merely noting the discrepancy to point out that one would have to assume that the linkage between export value and new infections only works when export value rises or drops precipitously for this linkage to work at all.  This misses my main point, which you failed to engage, which is that the correlation between export value and new infections is better explained by the rising availability of testing than it is by a greater amount of export motivated mobility among Ugandans.  The entire assumption that greater export value means more strangers means more spread of HIV bothers me something fierce -- a precipitous drop in export value might cause farmers to be uprooted and forced to migrate to urban centers which would entail (a) more exposure to HIV and (b) less ability to test for new infections because of all these suddenly appearing stranger ruralites.  The correlation is interesting, granted, but the conclusions Oster is drawing from them are unwarranted and highly contingent on the economic and social situation in Uganda.
--- End quote ---
Regression analyses are not inherently unreliable. In any case, her paper runs the same analysis on data from different sub-Saharan countries and test cases and finds strong case that the mechanism is real and not, as she specifically mentions, a secondary result of another contribution.

As to your main point, I apologize for ignoring it and will address it now: There is no support for your argument that the export-AIDS rate link is better explained by the "rising availability of testing". There was virtually no testing and definitely no reliable testing for AIDS in Uganda (and Africa) during the period of time Oster studied. Oster spent a good portion of her talk explaining how she had to derive the disease rate from death distributions and how she validated those figures.

She made other analyses of economic vs. HIV patterns in sub-Saharan Africa and found that it fit her model as well. (HIV rates in areas with lots of roads vs. areas with few roads, between truckers and their wives, etc). She did control for GDP and found that there wasn't a significant difference.


--- Quote ---Here you are demonstrably wrong.  Both the cumulative value and the quantity by volume or mass of exports are of interest to economists.  Oster seems to agree with me given that she discusses both correlation with value and volume in table 12 of her working paper.  Rising export value, which is what is correlated to new infections on the graph at 14:18 of the talk, is not what determines the amount of strangers circulating in Ugandan ports and towns spreading and catching HIV and thereby driving up the number of new infections.  No, what would drive up new infections is an increase in the volume of coffee trafficked, which would require a larger number of people to be present loading, shipping, and accounting for the coffee, which in turn would bring more strangers to Ugandan ports and towns, etc. etc.  Yet Oster draws the linkage between volume of exports in her talk and presents a graph comparing export value -- this is completely inadequate.
--- End quote ---
I was saying that value is what ties commodities together. When you know the value of a commodity, you know by extension how much of it there was. That's why a commodity is a commodity. But yes, volume is important, too. In any case, I was addressing your misunderstanding of why the decrease in exports was blamed on a drop in coffee prices. You can't just export more to make up for lower prices. If a coffee producer is getting less for his coffee, he can't afford to pay the people who grow, transport, and sell more of it; nor does it mean that the demand for more coffee is there even if the producer could produce more.



--- Quote ---So why, we might ask, did Oster present a graph comparing value instead of volume?  Table 12 of her working paper shows that according to her calculations, the value correlation explains about 60% of the drop in new infections whereas the volume correlation explains only 33% of the drop.  Of course, mentioning this in the presentation would have lessened the impact....
--- End quote ---
She presented the graph comparing value to HIV incidence because it was the better match to the incidence curve, not because it predicted a higher proportion of new infections. The export volume to HIV incidence model is just not as good a fit, as you can see by the R-squared values noted in tables 5 and 6. Note that the quality of fit is independent of the prediction of HIV incidence.

This implies that it is not so simple as you put it (more volume = more people spreading disease). Higher value could mean that producers are paying workers and drivers more, or are hiring more drivers, or buying more trucks (Oster actually analyzed truck imports against this data and got a positive correlation).


--- Quote ---I'm sure you know that I wasn't addressing my comments to TED participants, given that I posted them in the Questionable Content comic strip forums.  Oster is an assistant professor at the very beginning of her career who stood up in front of a group largely composed of people who were not academics and who did not specialize in her field, and made a series of very speculative inferences that she would never have made with the same confidence at an economics conference, and which only present the most exaggerated and worst supported data from her accompanying working paper.

Yeah, I think “pop presentation” is dead on.

--- End quote ---
Don't be so presumptive, considering how off the mark you are in your claims about Oster's talk. The fact remains that her presentation was to an audience of TED attendees, and she was invited to speak by the organization, and I doubt anyone would characterize them as gullible. TED is about new ideas, it's not a peer-reviewed journal. It's not as if she used any out-of-this world techniques or analyses in the paper. What is significant is that she applied those mundane techniques in a new direction and found surprising results.

RedLion:

--- Quote from: Patrick on 24 Mar 2008, 18:35 ---
--- Quote from: pilsner on 21 Mar 2008, 09:07 ---Borders in sub-Saharan Africa aren't like borders in the West. (snip) Every time there's a major upheaval, hundreds of thousands cross borders en masse seeking to escape violence.  Tight border controls for many of these countries are about as realistic as magic HIV curing pixie dust.

--- End quote ---

Idunno, there was that Peace Corps volunteer a couple months ago who tried to evacuate Kenya's election-related violence by hiding in a potato truck, and they got stopped at the border and all of them got turned back because she was unable to get her passport from the Peace Corps office, because, well, the capital was kindof going through a lot of urban warfare.

To be fair she was white and stood out like a goddamn neon sign in the heart of Africa, but the point is that some countries are finally able to control their borders more effectively. On the other hand, though, some countries don't want to control the borders, because the governments themselves are involved in illegal trafficking.

--- End quote ---

No, it's  true that (some) borders in Africa, particularly south of the Sahara (although the issue of Morocco/Western Sahara throws borders into disarray) are extremely porous, particularly around failed states like Somalia. Zimbabwe, in particular, has seen some 1/3 of its population flee across unguarded borders into Botswana and South Africa because of the utter annihilation of that country's economy (inflation is, no joke, running at 100,000 percent.) Another good example is the border of Sudan and Chad, where rebel groups from both countries that are loosely aligned with either Idriss Deby of Chad, or Omar al-Bashir of Sudan, trying to overthrow eachother by proxy, cross over the border with complete impunity. I mean, you have to remember that these borders were drawn up by colonial powers with no thought to tribe, culture or language. Often times, they just drew random straight lines.

pilsner:

--- Quote from: dennis on 25 Mar 2008, 18:20 --- If a coffee producer is getting less for his coffee, he can't afford to pay the people who grow, transport, and sell more of it; nor does it mean that the demand for more coffee is there even if the producer could produce more.

--- End quote ---

That's all supposition on your part.  More importantly, if you look at it the other way, greater volume (supply) would generally lower commodity prices.  Or so every Econ 101 text in the country seems to suggest.


--- Quote ---There was virtually no testing and definitely no reliable testing for AIDS in Uganda (and Africa) during the period of time Oster studied. Oster spent a good portion of her talk explaining how she had to derive the disease rate from death distributions and how she validated those figures.
--- End quote ---

Good point.  Where did the new infections by year in Uganda figures come from?  If she's working backward from the mortality figures that she derived from her age group analysis (which I don't believe she was), her results are even more skewed by false specificity than I believed.  But Oster stated in the talk that there were infected numbers in Uganda for certain populations, but not for the country at large.  I would hope that she would attempt to extrapolate from those numbers.


--- Quote ---She presented the graph comparing value to HIV incidence because it was the better match to the incidence curve, not because it predicted a higher proportion of new infections.
--- End quote ---

Your insight into Oster's motivations is remarkable.  I'm amazed that you don't find it suggestive that she produced wildly different "explanation" rates in her study but only presented the higher numbers in her talk.  If the Orioles batting average by season presented an even closer curve, should she have put that data up?  I'm thinking no -- because there's no basis for arguing causation.  Then why work off of export value? 


--- Quote ---Higher value could mean that producers are paying workers and drivers more, or are hiring more drivers, or buying more trucks (Oster actually analyzed truck imports against this data and got a positive correlation).
--- End quote ---

Higher export value means paying workers and drivers which spreads more HIV.  Dude, I am just amazed.  This is fantastic stuff.  Maybe they're hiring more hookers with their extra money.  We could call it the governor theory of HIV epidemiology.  You should definitely write a paper.


--- Quote ---TED is about new ideas, it's not a peer-reviewed journal.
--- End quote ---

Agreed!

Patrick:

--- Quote from: RedLion on 25 Mar 2008, 19:33 ---I mean, you have to remember that these borders were drawn up by colonial powers with no thought to tribe, culture or language. Often times, they just drew random straight lines.

--- End quote ---

I'm pretty sure that's exactly where the vast majority of Africa's problems lay.

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