• by Joe Mandese  @mp_joemandese, November 13, 2006

For the second time in less than a year, Nielsen Media Research has redefined the meaning of time. Under its new definition, any TV programming or advertising viewed within 25 seconds of its original telecast will now be considered "live," and anything viewed after that will be credited as playback. Nielsen's previous definition of live viewing, adopted in January, was any content viewed within eight seconds of its original telecast.

Nielsen began expanding its definition of live early this year when it began encountering new generations of TV set-top devices, particular newer digital video records, which automatically delay what viewers see. When it announced the eight second rule in January, Nielsen warned that it might expand it later if it encountered longer "machine time" delays in future generations of TV technology.

Nielsen did not say explicitly what caused it to expand its time-delay rule this time, but in a notice sent to clients late last week, the TV researcher it made the move, "The revised threshold is necessary to account for transmission delays, delays introduced by in-home equipment, and delays introduced by software in certain DVR set-top boxes."

In fact, Nielsen executives have said a number of delays have been occurring throughout the "transmission line," not just on DVRs and other devices in TV households, but form satellite and cable head-ends as well.

In January, Nielsen executives said these anachronisms often lead to a "mismatch" between Nielsen's "metered time" and the actual time of telecasts viewed within a TV household. Nielsen said it needed the extra buffer time to reconcile the differences, but at 25-seconds the amount of buffering is getting uncomfortably close to the length of Madison Avenue's standard advertising unit, the 30-second commercial.

It's also unclear how the 25-second rule might impact the commercial minute ratings data Nielsen plans to begin providing the industry early next year.

Meanwhile, some Nielsen clients were miffed in the way Nielsen communicated the new rule, days after it held a series of national client meetings in New York, Chicago and Los Angeles, and on the eve of a national holiday - Veteran's Day - abutting a weekend. The handling of the announcement, they said, may have been designed to minimize discussion about the move.