What is the test for finding a juror guilty of misconduct?

When a party alleges juror misconduct, "the trial court must determine . . . whether misconduct occurred and, if it did, whether the misconduct was prejudicial." (People v. Loot (1998) 63 Cal.App.4th 694, 697.) If misconduct occurred, prejudice is presumed, but "[t]his presumption can be rebutted by a showing no prejudice actually occurred or by a reviewing court's examination of the entire record to determine whether there is a reasonable probability of actual harm to the complaining party." (Ibid.) "In deciding whether misconduct was prejudicial, the trial court must determine whether there exists a substantial likelihood that some extrinsic material or information improperly influenced the vote of one or more jurors." (People v. Dorsey (1995) 34 Cal.App.4th 694, 704.)