What is the test for assessing credibility in a medical malpractice case?

This policy goes on to provide that a conclusion against the statement of a worker about his or her own condition may be reached if the conclusion rests on a substantial foundation such as clinical findings, other medical or non-medical evidence or serious weakness demonstrated by questioning the worker, or if the statement of the worker relates to a matter that could not possibly be within his or her knowledge. I have also considered the test for assessing credibility as set out in Faryna v. Chorny noted above.