Have there ever been any studies of jury performance based on selection rules for the juror pool? For example, I sat around several times at Cook County courthouses waiting to be called, and the evident quality of potential jurors was pretty decent: a lot of guys in business suits reading the WSJ. Among potential jurors in LA County courthouses, however, you have a lot of people sitting around staring blankly. My impression is that this is due to where names were drawn from at the different periods in different places: voter registration roles in Cook County in the 20th Century, Department of Motor Vehicle rolls in Los Angeles County in the 21st Century. There are a lot of opportunities for social sciences studies here, such as natural experiments of the impact when the source of the jury summons gets changed.
In general, however, most Americans don`t seem to want to think about just how badly juries often perform.