Jury selection can get very sophisticated indeed. When I was at Duke University my statistics professor had a sideline as a jury consultant. (In fact one day I walked in on him speaking on the phone with the actor, Marlon Brando, whose son was having some very serious legal problems at the time). Marlon was apparently fascinated by the whole jury selection process. My professor would be paid to conduct surveys in the areas where the jury pool would come from, to assess relevant attitudes and beliefs and to identify characteristics predictive of those attitudes and beliefs. Based on this work, he would advise the defense counsel to select, say college-educated women who did not go to church and to avoid men with military backgrounds and more than two children, etc.
Eric