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

We are here again confronted with the too-often ignored rule that where the findings are attacked for insufficiency of the evidence, our power begins and ends with a determination as to whether there is any substantial evidence to support them; that we have no power to judge of the effect or value of the evidence, to weigh it, to consider the credibility of the witnesses, or to resolve conflicts in the evidence or in the reasonable inferences that may be drawn therefrom. (Overton v. Vita-Food

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