PVRs have no effect on US household purchase habits

"No matter how the researchers looked at it, DVRs did not affect what people bought. This conclusion astonished the researchers.
“Our initial goal was to simply measure how bad DVRs were for advertisers,” Mela says. “We tried a vast array of methodological approaches to find a DVR effect. And we just couldn’t.”
Mela offers these factors to account for the lack of a TiVo effect:
- To fast-forward a commercial, users must record a show to watch later. But TiVo households still watch the huge majority (95 percent) of their TV live, meaning few commercials can be skipped.
- Households without a TiVo can still avoid commercials. They can take a kitchen break, flip to a different channel, or find other ways to divert attention during commercials. This means the DVR might not increase ad avoidance as much as feared.
- Even though consumers fast-forwarded through about 70 percent of commercials in shows they recorded, they don't actually "skip" them. By concentrating on the screen to know when to press play and resume their show, those who forward are often exposed to the advertising they supposedly "skip." "
Source: Professor Carl L. Mela of Duke University’s Fuqua School of Business, reported by Physorg,com, 3rd May 2010
Methodology: In partnership with Information Resources Inc. (IRI) and TiVo, Mela and colleagues from The University of Chicago and Tilburg University conducted a multimillion-dollar, three-year field study in which some households were given a DVR and their shopping behavior was compared to those without one. The authors tracked purchases of new products, advertised products and store brands across 50 categories as well as the viewing behavior of those with the DVRs.