It's one of the most impressive statistics about the new health care law. The Obama administration says more than 8.9 million people have been, quote "determined eligible" for Medicaid from Oct. 1 through the end of January. But a new study Monday from Avalere Health estimates the actual number of new sign-ups could be much lower, between 2.4 million and 3.5 million. The administration's statistic also includes many people renewing existing coverage. Medicaid is a safety-net health program for low-income people.