From what I understand, yes this would be an example.

I would like to be able to make use of ideas from the lecture on recipricol causation, but I am having trouble seeing how to get started. My overall goal is to come up with a model that can be applied to any county to obtain an estimate of the dollars of insurance premium an insurance company would collect if they had an agent in that county. There are 3,100 counties of which about 300 already have agents. Causality clearly runs both ways: agents cause premium, and premium causes agents. We collect more premium in counties where there are agents because although the agents are free to sell policies anywhere, they tend to sell them close to home. Just as clearly, agents set up shop where they think they will be able to make sales so the presence of premium causes there to be agents. If I could cause there to be an agent in a county where there isn't one now, I should see increased premium only to the extent that agents cause premium and not to the extent that premium causes agents. Does this seem like an example of the sort of problem Gary was addressing in yesterday's lecture? If so, is my first step to think of some explanatory variables for the presence of agents that do not also explain the presence of premium? That may be difficulat since presumably, agents go where the premium is. (If a certain mix of SIC codes, growth rate, and population density causes high available premium, then it indirectly also causes there to be agents.) -Michael ------------------- Michael J. A. Berry Harvard email account (Permanent email: mjab(a)data-miners.com) _______________________________________________ gov2001-l mailing list gov2001-l(a)lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov2001-l