What is the test for proving a plaintiff's negligence in a medical malpractice case?

"Where there is evidence that the harm could have occurred even in the absence of the defendant's negligence, 'proof of causation cannot be based on mere speculation, conjecture and inferences drawn from other inferences to reach a conclusion unsupported by any real evidence.' " (Padilla v. Rodas (2008) 160 Cal.App.4th 742, 752 (Padilla); see also Jones v. Hotchkiss (1956) 147 Cal.App.2d 197, 202 (Jones) [reasoning that the plaintiffs must show some evidence of negligence causing a dangerous condition on a slippery floor beyond mere evidence of a fall].) Viewing the evidence in a light most favorable to plaintiffs, we agree with defendants.