DVRs also significantly lift "L3" ratings over "live-only" in the 18-to-34 demo by 24% -- and among adults 25 to 54 by 20%, on average. Even among viewers 55-plus, "L3" ratings increase 7% in prime time.

Data for local markets also shows that while 90% of DVR playback takes place within three days, 75% occurs within just one day. Further evidence that people may be looking to avoid commercials: 20% of playback takes place within only five minutes of live broadcast.

The data comes from a report that Nielsen sent to a select group of clients. Prime-time ratings do not include the 10 p.m. to 11 p.m. hour.

The new "L3" data is derived from "program ratings" and not the "commercial ratings" used in national TV buying as a currency. Before January, Nielsen had only offered "live" and "live plus seven day" overnight data streams.

As of last November, some 29% of households in Nielsen's local people meter and local set meter markets had one or more DVRs.

As with national ratings, the "live plus three" or "L3" local numbers show that DVR viewing can lift the overall performance of a show. In the 18-to-34 demo, "The Office" is ranked sixth in "live" viewing, but soars to first in "L3."

"Grey's Anatomy" moves from fourth to second thanks to the added ratings, while "30 Rock" rises from twelfth to seventeenth and "Heroes" from thirteenth to ninth.

In cable for 18-34 viewers, FX's "It's Always Sunny in Philadelphia" jumps from tenth in "live" viewing to third in "L3." MTV's "The Hills," with its younger-skewing audience, is also a strong mover up the charts from eighth to fifth.

For the local markets, the data also shows that DVRs can alter audience composition. For live prime-time viewing, 27% of the PUT (persons using television) are ages 25 to 44. That figure increases to 48% for playback within three days.

Not surprisingly, higher-income homes tend to use DVRs more. In the local markets, 20% of the households using television (HUT) live in prime time have incomes of $100,000-plus. That increases to 38% of the HUT for playback within three days.

"L3" ratings versus "live only" for Spanish-language stations in local markets did not increase appreciably. In the 18-to-49 demo, "L3" numbers were up 2% on average -- compared to 21% for general-market stations.

Also, cable viewing in local markets did not increase at a level near what occurred at English-language broadcast stations. In the 18-to-49 demo, ad-supported cable ratings on average in prime time were up 5% for "L3" versus live.

Until January, Nielsen provided only "live" and "live plus seven" streams for local markets. The measurement company does not provide "commercial ratings" for local TV -- something buyers covert -- partly because local ratings are based on "average quarter-hour" viewing. National ratings come from "average minute."

A switch to "average minute" in the local arena would need to be made for Nielsen to offer "commercial ratings" for local TV.

On the national level, advertisers and networks have settled on the "C3" ratings as currency. At the local level, broadcasters (spearheaded by the Television Bureau of Advertising) are looking to make deals based on an "L3" currency, seeking to gain some credit for DVR viewing.

But resistant buyers say that until commercial ratings come into play, "live-only" ratings are necessary, since "L3" offers no details on commercial-zapping levels.

Still, the Nielsen report was able to use some analysis to provide a gauge for the impact that commercial ratings might have, if brought to local people meter markets. Comparing "C3" to "live commercial ratings" in the 18-to-49 demo shows an increase in the "C3" metric by 10% on average (at English-language stations).

The Nielsen report data also shows that the audience watching in three-day playback mode includes a higher level of "prospects" for new-car buying (19%) versus 14% of those watching live.

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