Taking into account the impact of digital video recorders (DVRs) on the value of commercials, Nielsen Media Research will begin to issue two new sets of program data in addition to the existing ratings for real-time (or "live") viewing, reports AdWeek. Starting Dec. 28, Nielsen will also issue same-day program playbacks, and on Jan. 17 it will issue seven-day program playback ratings. It says on 90 percent of played-back DVR viewing occurs within seven days.

But the ratings would likely not be used to buy and sell ads, at least for now, because only 60 DVR homes would be included in its 9,000-home national ratings sample.

However, Nielsen plans to add about 100 DVR homes per month to the national sample until July 2006, to come up with a representative sample.

For advertisers, the question is, still, to what extent viewers will use DVRs to zap commercials. Studies have come up with widely varying figures.