•What's the probability of my having a cavity given that I stubbed my toe?
•Often, there is no direct causal link between two things:
–direct: burglary à alarm cavity à toothache
– disease à
symptom defect à failure
–indirect: burglary à alarm company
calls
– cavity à
dentist called about toothache
– disease à
symptom noted
– defect à
failure caused by failure
