Re: Bayesian Networks and Belief Functions

Judea Pearl (judea@cs.ucla.edu)
Tue, 8 Jun 1999 21:49:27 -0700 (PDT)

Kathy,
You say:
No matter what prior probability we put on Q, the marginal probability
of R in any probability model would lie between 0.8 and 0.9.
One can "explain" the phenomenon (i.e. Bel(R)=0.72)
by saying that there is only a 0.72 chance that "the
evidence would prove R," but I was never able to come up
with a way to argue this convincingly to a subject matter expert.

This was one of my problems too, but watch how sensible it
sounds when translated into the scheduling example I gave:

"No matter what prior probability we put on Q, the probability
that I will be assigned to teach class R would lie
between 0.8 and 0.9.
Still, the probability that I WILL BE FORCED to teach
class R, for lack of an alternative consistent
assignment, is 0.72."

Do you find any difficulty explaining this to
a subject matter expert?

============Judea