Sunday, October 11, 2009
Auld DQs
This paper is a bit hard going, mathematically. See how far you can get, but mainly try to get the gist of the interaction between behavioral and epidemic dynamics. Do you buy the argument, in general? Try to distinguish between behavioral responses to information about the current environment (worse = you should be more careful) and information about future environments (worse future = heavy discounting = get it while you can).
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I'm a little unclear on what they mean by rational. For instance, on page 370: "Agents with rational expectations are rational given beliefs and form beliefs rationally. They act as if they know current and all future per-contact infection probabilities..." How is acting as if you know your contact probabilities rational?
ReplyDeleteI would also expect that, given an effective enough vaccine, that prevalence would decrease even if risky behavior increased (see top of page 373).
I'm also reluctant to completely buy into the assumption that risk behavior increases if future transmission probabilities are perceived to be high. The prevalence of some types of risky behaviors (e.g. the use of bathhouses) changed dramatically in some areas (e.g. San Francisco) after the start of the epidemic, even though in the early stages of the epidemic there was not ART nor a vaccine in the near future.
(1) "Rational" means that based on the information you have/believe, you act to maximize your utility (i.e., have the desired current and future number of partners, weighted by the disutility to you of getting sick). (2) if a vaccine is effective and widely administered, then yes, it trumps behavior. (3) presumably the behavior changes you're talking about were responding to perceptions of *current* risk.
ReplyDeleteIts an interesting concept associating a pessimistic future projection for the spread of a disease with an increase in behavior that could directly result in exposing oneself to infection. However I am not sure I can agree fully with this line of logic. I could see how people already engaged in risky behavior at a given level would maintain that level of risk in the face of a possible increased future risk however I find it hard to see how individuals would consciously increase their level of risky behavior especially given the lethal implications of infection.
ReplyDeleteFear is a powerful motivator (as demonstrated by our previous presidential administration). However I fail to see the connection with an increase in engagement in risky behavior to the point that it could alter the trajectory of an infectious disease, such as what is presented in Fig 2.
I also have a question with Fig. 3. If the simulation was projected further into the future would the benefit seen from the release of the vaccine eventually decrease through selection for drug resistance strains? (especially given the current rates of increase seen in the four years post release).
Section 3.1.1
ReplyDeleteDo we assume that infected agents know that they are infected? Isn’t this a fundamental bit of information to include in decision making- or at least split infected into two decision making groups- those who know they are infected and those that don’t? And, I am not sure what they mean by a static optimization problems? It makes sense that individuals in this category will probably not change their decisions much with and without the vaccine (and when it is announced) but Id like a bit of clarification about what this term means
I am also interested in how you can evaluate the benefit/value of having a sexual partner. I would think that if you are a highly active person, you would actually benefit relatively less for each new partner you acquire (that partner is valuable to you for a brief period of time). Compare this to a monogamous couple where the value of acquiring that partner is very high (financial stability, etc...). I know that we need to simplify values that go into these dynamic models but I am just interested in how these economic models evaluate the magnitude of a benefit, or cost.
Sorry I cannot make it to class tomorrow everyone. I’ll be there and ready to go on Wednesday.
@adam: I don't know about "consciously adjust" -- the argument is simply that (in many cases at least) people *do* adjust their behavior in response to risks and benefits, even balancing lethal risks against non-lethal benefits (driving on the highway, crossing the street in traffic ...)
ReplyDeleteRemember that this is all *deductive* logic -- provided there are no mistakes in the math, if you disagree with the conclusions you must question either the premises of the argument, or the interpretation of the results -- you can't question that the results follow from the premises
Strange paper. First off, I agree with Christine that a valuation of additional sexual partners seems like a difficult task. All in all, it's hard for me to buy into the idea that expectations over the future of the epidemic will so decisively change current behavior of individuals in a population. In particular, it seems very reckless that anyone would increase risky behavior given a dismal future outlook, or the announcement of a vaccine. The concept behind economic epidemiology is an interesting one, but accurately predicting behavioral responses among a diverse population of adults in order to map out disease dynamics through time seems a bit like an exercise in futility.
ReplyDeleteAlso, as criticism, the mathematical notation in this paper seemed like it was more complicated than it needed to be (I had trouble following). Also, Figure 3 was hard to swallow: Does this assume that the transmission coefficient in indefinitely suppressed? Also, regarding the anticipated vaccine scenario, it seems hard to believe that so many new infections would arise from risky behavior so as to completely offset the release of an effective vaccination. I feel like it would be more likely that the disease would receive increasing attention and publicity prior to vaccination release that would keep people from acting so stupid. Maybe I have too high of expectations for general common sense.
-Mike
As some of you have said (I think) it seems that not knowing the differences in risky behavior between infected vs. uninfected people sort of confounds the results. One would think that pessimism may drive knowingly infected people to be more risky, but not knowingly uninfected people. Perhaps? If there a pessimistic outlook I would think the knowingly uninfected would be less risky. Basically, I think we need to consider differences in riskiness between those who know and do not know that they are infected. Wow, that was excessively redundant. See you all in class.
ReplyDeleteThis is an interesting paper. I found a great logic respect with simulation, specially with the idea of taking a model in which "Homo economics" can learn and choose. In addition, it is fascinating the way in which an announced vaccine and a released vaccine could change futures. However, I am not totally agree with it, because I have the idea that models need a mechanistic feedback. Without a mechanistic feedback for constructing models conclusions may be vague.
ReplyDelete