What is the test for determining whether a prosecutor exercised peremptory challenges in a discriminatory manner?

Contrary to appellant's belief, there was nothing improper about the court determining whether the record contained sufficient evidence from which to infer that the prosecutor had exercised peremptory challenges in a discriminatory manner. It is only after finding that a prima facie case has been established that the trial court is precluded from speculating as to why a party exercised its peremptories and is required to ask the party for his or her reasons. (People v. Lancaster (2007) 41 Cal.4th 50, 75-76.)