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Pneumonia Hypothesis Probability

The third hypothesis has the intermediate nodes for low LVF and high LAP false. The probability of this is also calculated by following the causal pathways. The probability of the pneumonia is 0.01 and the probability that it causes PC is 0.5. The probability that the MI did not produce low LVF is 0.4.

There is also opportunity for local optimization of this hypothesis by adding nodes. Since the probability of low LVF is higher than the probability of it being false, the program explores whether this leads to a better hypothesis. The highest probability scenario corresponds to the time intervals in the hypothesis with high LAP corrected by nitroglycerin. The primary difference is that there are now two causes for PC and the probability of PC is , using the default combination rule. Thus, if those two nodes are added to the pneumonia hypothesis, the probability becomes 0.0029.

Thus, the HDP is able to rank order the hypotheses and say that the most likely hypothesis is that the nitroglycerin corrected the high LAP. About a third as likely is the hypothesis that the low LVF normalized. About 1.5%as likely is that pneumonia was at least partially the cause for the pulmonary congestion.


wjl@MEDG.lcs.mit.edu
Fri Nov 3 16:57:00 EST 1995