Would the opening greeting on “Saturday Night Live” sound as compelling if it began “Live plus 24 hours from New York” or “Live plus seven days from New York”? That is the multibillion-dollar question being asked on Madison Avenue as agencies and advertisers consider the implications of new data from Nielsen Media Research on television viewing in households with TiVos and other types of digital video recorders.

Late in December, Nielsen, part of VNU, started distributing its ratings information in three versions: live, the traditional way television is watched; live plus 24 hours, counting how many people who own DVR’s played back shows within a day of recording them; and live plus seven days, counting playback within a week of recording.

For some prime-time series, like the hit drama “Grey’s Anatomy” on ABC, the so-called live-plus ratings show slight but noticeable gains compared with the live-only viewership. But it is estimated that 50 percent to 70 percent of viewers playing back shows zip through the commercials, casting doubt on their worth to advertisers.

Nielsen’s adoption of the new methodology was spurred by the growing use of digital video recorders, which are already estimated to be in 7 percent of the nation’s 110.2 million TV households. DVR’s are among the technologies that are starting to remake the way people watch television, along with video iPods, video-on-demand and broadband connections for personal computers.