This paper is primarily the report of two different major applications of set-top box data. One application involves the full-time measurement of all 300+ channels over a 12-week period in 8,700 set-top boxes in 6,292 homes in one U.S. market. The other application involves the measurement of selected commercials and programs on 28 broadcast and cable networks in over five million set-top boxes in an average of 3,909,965 million homes connected to a backpath over a three year period across the entire U.S. In both cases, set-top box based audience measurement was a side effect of the studying of the phenomenon of interactive television, in one case focusing on its targetability aspect and in the other case focusing on its interactive aspect. This provides insight both into the main subject of this paper, set-top box based television audience measurement, and the secondary subjects of this paper, the performance characteristics of interactive and addressable television.