What is the test for reversal of a finding of not guilty on the basis of erroneous admission of expert testimony?

erroneous admission of expert testimony only warrants reversal if 'it is reasonably probable that a result more favorable to the appealing party would have been reached in the absence of the error.'" (People v. Prieto (2003) 30 Cal.4th 226, 247; People v. Coffman and Marlow (2004) 34 Cal.4th 1, 76 (Coffman) [claim of inadmissible opinion testimony on issue of guilt is "one of erroneous admission of evidence, subject to the standard of review for claims of state law error"].)