What is the test for deliberative error in a jury in a personal injury case?

Similarly, here we have, at most, a "deliberative error." (Contrast Tapia v. Barker, . supra, 160 Cal.App.3d 761, 206 Cal.Rptr. 803, where juror discussions showed jurors considered reducing the judgment based on outside evidence of a collateral source of income as well as the fact a juror had an improper, unrevealed bias against the plaintiff's Mexican background.) On this issue, the declarations do not reveal the use of any outside evidence or resort to outside legal authority. The declarations indicate, at most, confusion or misunderstanding by the jury in the process of deliberating, in determining how to reach a verdict using the instructions given to them by the court. This error is not the type that can be used to impeach a verdict.