Quote from Jerry030:
Who really cares about the details of the process if you can clone it in terms of results?
Quite simply because any curve can be fit perfectly with enough degrees of freedom -- but it doesn't mean that it can predict the next point with any measure of accuracy (in fact, quite usually, it will do worse than a more robust fit with less degrees of freedom).
The primary issue is that even though the input and output are easily measured, it is impossible to define the set of methods I am using to work with that data. Am I tossing out data older than 5 minutes? Am I fitting gamma-distributions from samples and trading spreads? Am I building interpolating spines with variable time windows to reduce noise? Am I removing the time-frame and translating into constant tick or volume measures?
The point being, with all these possibilities, unless you know something about my strategy (and that is a big IF), you most likely won't be able to reverse engineer it with such simple input / output. In fact, the more complex the input / output, the EASIER the job would be to a certain degree (e.g. translating Japanese codes in WWII). But with only price / volume and BUY / SELL, it becomes near impossible to define a domain of methods to replicate with...
Unless ... and this just struck me -- could it be possible to define a set of 'eigen indicators' -- a set of processes that almost any strategy can be broken down into a (non)linear combination of? Wouldn't that be strange... If so, well, maybe it would be possible to reverse engineer rather easily...