WASHINGTON (AP) — The number of young adults lacking medical coverage has shrunk by 2.5 million since the new health care overhaul law took effect, according to a new analysis the Obama administration is to release Wednesday.

That drop is 2½ times as large as the drop indicated by previous government and private estimates from earlier this year, which showed about 1 million Americans ages 19-25 had gained coverage.

Administration officials said they now have more data. They say they're also slicing the numbers more precisely than the government usually does, trying to pinpoint the impact of a popular provision in an otherwise politically divisive law.