On its face, the low-key discussion around a conference table in Miami last month did not appear to have national implications. Eight men and women, including a diner owner, a chef and a real estate agent, answered questions about why they had no health insurance and what might persuade them to buy it. But this focus group, along with nine others held around the country in November, was an important tool for advocates coming up with a campaign to educate Americans about the new health care law. The participants were among millions of uninsured people who stand to benefit from the law.