This story was a collaboration between ProPublica, WNYC and Marketplace, and is part of an ongoing investigation by Charles Ornstein and Tracy Weber of ProPublica.

Medicare Part D, which provides medications to 36 million Americans by giving seniors and the disabled access to prescription drugs, is often described as a healthcare success story, coming in below cost estimates.

But when ProPublica looked closely at Medicare’s prescription data, they found hundreds of millions of dollars a year were being wasted — all because a small percentage of doctors prescribe name-brand drugs instead of lower-cost generics, even when the generics work just as well. Right here in New York City, these doctors could save Medicare over $50 million a year.

WNYC teamed up with ProPublica to find out: why? We started by visiting 1220 Avenue P in Brooklyn, the Levit Medical Center. If just six doctors at this one address prescribed in a different way, they could have saved Medicare $1.8 million dollars in 2011 alone.Want to find out how your doctor is prescribing? Check out ProPublica’s Prescriber Checkup. Type in a physician’s name or zip code and you’ll find out more about how physicians spend Medicare’s money.