Nielsen Media Research (NMR) is an American firm that measures media audiences, including television, radio, theatre films (via the AMC Theatres MAP program) and newspapers. NMR, headquartered in New York City, is best known for the Nielsen ratings, an audience measurement system of television viewership that for years has been the deciding factor in canceling or renewing television shows by television networks. As of May 2012, it is part of Nielsen Holdings.