What is the test for admitting or excluding expert testimony in a medical malpractice case?

[Citation.] 'That is not to say, however, that the jury need be wholly ignorant of the subject matter of the expert opinion in order for it to be admissible. [Citation.] . . . Rather, expert opinion testimony "'will be excluded only when it would add nothing at all to the jury's common fund of information, i.e., when "the subject of inquiry is one of such common knowledge that [those with] ordinary education could reach a conclusion as intelligently as the witness"' [citation]." [Citation.]' [Citation.]" (People v. Brown (2014) 59 Cal.4th 86, 101.)

"'The trial court has broad discretion in deciding whether to admit or exclude expert testimony [citation], and its decision as to whether expert testimony meets the standard for admissibility is subject to review for abuse of discretion.' [Citation.]" (People v. Brown, supra, 59 Cal.4th at p. 101.)