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Tracking, Again

So I finished reading a large number of studies on tracking. One thing that I noticed, there is a general assumption that you should start with cheaper methods and go to more expensive. But that might not always be true. For instance, what if a cheap method almost never returns a result, while something more expensive produces more leads. I could imagine skipping the cheap step, or putting it after the expensive step.

In any event, it is really a sequence of steps that needs to be optimized. How to do this involves both the costs and the expected returns. But since each of those are only known conditionally upon whatever was done prior to the current step, we need experiments that vary the order of the steps to find out what the optimal step is going to be.
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