Use this source to look up terms used for measuring audiences, advertising and marketing for all kinds of broadcasting, print, and online media. This dictionary is part of the Oxford Reference Online collection.

http://tc.liblink.umn.edu/sfx_local?sid=OUP%3AORO&date=2011&title=A%20Dictionary%20of%20Media%20and%20Communication&isbn=9780199568758&genre=book