Nielsen ratings are the audience measurement systems developed by Robert F. Elder and Louis F Woodruff and sold to Nielsen Company, in an effort to determine the audience size and composition of television programming in the United States. Nielsen Media Research was founded by Arthur C. Nielsen, a market analyst whose career had begun in the 1920s with brand advertising analysis and had expanded into radio market analysis during the 1930s, culminating in Nielsen ratings of radio programming, which was meant to provide statistics as to the markets of radio shows. The first Nielsen ratings for radio programs were released the first week of December 1947. They measured the top 20 programs in four areas: total audience, average audience, cumulative audience and homes per dollar spent for time and talent.