Which is best? Likelihood method is ``best,'' but
method is computationally easier as .
Typically, as number of events in each bin must be large
method will give an estimate with a larger standard
deviation, but the difference will not be large if
is small, so probabilities do not vary across bin.
So, can choose correctly
Small total number of events---no good method.
Large number of events--Maximum Likelihood works and is best.
Very large number of events---Maximum Likelihood and
works, but will give a good answer with less computational
complexity.