Graham, it's worse than they are telling you. If this offends, sorry, just reporting from personal experience.
I have been called a few times, been dismissed most times. Both sides have an agenda and try to load the jury with acceptable jurists. Sounds like it should be fair right, both sides question the potential jurists. But, who are the potential jurists? The first time I was called, I had paid for a trip to Argentina. Judge said dismissed, you are back on the call list. I was in fact called again very soon. Military duty, being a business owner, having a decent living wage and having an opinion kept me off most other cases. So when I finally served, the other 11 were either women with already grown children or the unemployed.
You will never have a representative jury under thew current system. When those with money or connections are dismissed, and those with convictionms are ineligable, it's just not possible.
Sorry, I'm ranting.
David