What is the test for establishing a prima facie case in a civil case?

To establish a prima facie case, the defendant "must show a strong likelihood that such persons are being challenged because of their group association rather than because of any specific bias." (People v. Wheeler, supra, 22 Cal.3d 258, 280, 148 Cal.Rptr. 890, 583 P.2d 748.) In determining whether the defendant has made such a showing, trial judges may "bring to bear on this question their powers of observation, their understanding of trial techniques, and their broad judicial experience." (Id. at p. 281, 148 Cal.Rptr. 890, 583 P.2d 748.)