I am looking for a statistical technique similar to a estimating a hazard model.
Suppose a person chooses between two actions, buy or sell. Given data on trading decisions, once a person has bought, say, a stock, I can calculate the time that elapses until they sell. Using a hazard model I can model this hazard as a function of other variables. This allows me to answer questions about what predicts a person's decision to sell.
But this ignores the fact that sometimes instead of selling a person buys more stock. This is the opposite of selling, and moves the person further away from "failure" (ie, selling). I can think of no analogy in epidemiology, which perhaps explains why I haven't been able find a method that is suitable for this situation.
Any suggestions for techniques that may be useful here would be greatly appreciated. Thanks!