Are you, then, trying to find which event gives you the most information about whether or not B occurred?
Yes, that's it. It is just that some of the tests are much more expensive, to the point that I won't be able to do them routinely,but others wwhich are quick and easy to perform might not give me the necessary information.
I think it's past time for another Stupid Questions thread, so here we go.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Please respect people trying to fix any ignorance they might have, rather than mocking that ignorance.