Adults in households with digital video recorders watch less TV than adults in the general population, according to analysis by Mediamark Research. The finding, which comes from in-home interviews with 26,000 adults seems to conflict with the contentions of the major broadcast networks. Researchers for the networks told advertisers in November that people in households with a DVR watched 12 percent more hours of TV a day than those without. Those researchers had argued that that tendency counterbalanced the possibility that DVR users would skip past ads.

CBS, said the Mediamark numbers were unreliable, because they were derived from people's often-low reports of their own TV watching. The figures suggesting that adults who use a DVR watch more television come from Arbitron's 2,000-person machine-recorded survey in the spring of 2005, but covered only the Houston market. CBS said according to proprietary research, people with DVR's, whatever their level of TV viewing, tended to watch more television after getting the devices than they did before.