What is the standard of review for a motion for a new trial based on juror misconduct?

We review those findings under the deferential standard of review set forth in People v. Dykes (2009) 46 Cal.4th 731, 809, as follows: "The trial court is vested with broad discretion to act upon a motion for new trial. [Citation.] When the motion is based upon juror misconduct, the reviewing court should accept the trial court's factual findings and credibility determinations if they are supported by substantial evidence, but must exercise its independent judgment to determine whether any misconduct was prejudicial. [Citations.]"