ANN ARBOR, Mich. -- From Massachusetts to Hawaii, many states, counties and cities are working on ways to provide new health insurance options to the 45 million Americans who lack health coverage.

But the devil's in the details: Which treatments and preventive measures will the new plans cover? How much will they charge for doctor's visits and trips to the emergency room? Which doctors and hospitals will accept them? How much will they cost?

A new study published in the November issue of the journal Health Affairs reveals a promising way to deal with this thorny problem: Let the public decide.

In fact, the study suggests, grassroots decisions about what's fair, and what's affordable, may lead to coverage that will be acceptable to participants even though they are less costly than average health plans.

The study involved nearly 800 California residents from diverse backgrounds who took part in a project that asked them to design the best possible health plan for the uninsured, using a limited amount of dollars. The project, funded by the California HealthCare Foundation and organized by the nonprofit Sacramento Healthcare Decisions, used a game-like computer program called CHAT (Choosing Healthplans All Together) developed by University of Michigan and National Institutes of Health researchers.

Individually, and in small and large groups, the 798 participants picked from a range of options including different coverage levels for preventive, chronic and last-hope care; different options for access to doctors; a variety of co-pays for appointments, hospital stays and ER visits; options for dental and vision care, different premium levels, and more.

Each of the options "cost" them a certain number of points, which were calculated based on actuarial estimates of the real-world costs of those coverage options. Just like in the real world, the amount of points (dollars) available to spend was limited.