EXAMPLES
Consider the following example.
| Possible Signs |
Signs Present |
Diagnoses |
Beliefs |
| aaaaaaa |
fever |
Mastitis |
0.992 |
| bbbb |
changes in milk |
Metabolic Diseases |
0.007 |
| cccccccccccc |
sudden milk drop |
Anaplasmosis |
0.001 |
| ddddddd |
wasting |
|
|
| eeeeeeeee |
|
|
|
After entering 4 pieces of evidence, the belief network
evaluates only 4 diseases as having non-zero beliefs. Of these,
mastitis has such a high belief that it appears by far the most likely
scenario.
By contrast, consider the following scenario:
| Possible Signs |
Signs Present |
Diagnoses |
Beliefs |
| aaaaaaa |
anaemia |
Babesiosis |
0.510 |
| bbbb |
fever |
Acute Trypanosomiasis |
0.388 |
| cccccccccccc |
lethargy |
ECF |
0.090 |
| ddddddd |
diarrhoea |
Metritis |
0.008 |
| eeeeeeeee |
inappetance |
Chronic Tryps |
0.005 |
| ffffff |
sudden death |
|
|
| gggggg |
|
|
|
Although 6 pieces of evidence have
been entered, and most diseases have been excluded
from consideration, of those which remain possible, 2
diseases are broadly plausible, 2 cannot be discounted (since
they have low, but not minute belief ratings), and 2 can probably
be discounted as highly unlikely. It would be very wrong to interpret this
screen as stating that the correct diagnosis is babesiosis. Rather,
babesiosis and acute trypanosomiasis should be regarded as likely causes
of the observed signs; ECF and anaplasmosis as possible causes and a clinical
sign or laboratory test should be sought to distinguish
between these different possibilities.