Nielsen's slated spring introduction of a measurement system that would have used digital video recorders to determine how - or if - people watched TV shows and, presumably, the commercials that go with them, has been set back to the beginning of 2006. Media buyers have been frustrated by Nielsen's slow adoption of technology that would better show how viewers are actually consuming television, skipping ads, recording and reviewing previous programming and other behaviors thought to be increasingly common. The DVR measurement system is very likely to show that TV ads are watched less than suggested by other Nielsen measurement means, which has proven an unpopular prospect among TV companies. No reason was given for the delay. Popular DVR maker Tivo announced last November that Nielsen competitor IRI would also use the data to help measure commercial effectiveness.