However, a Nielsen spokeswoman pointed out that the immediate potential impact of this technological breakthrough is slight.
"When we go into a metered home, we connect our equipment to every piece of television or video equipment we find there," said Anne Elliot, vice president of marketing communications. "TiVO currently accounts for less than 1% of all our 30,000 metered samples."
Other PVR makers
TiVo is the only personal video recorder technology Nielsen can currently monitor, Ms. Elliot said. Nielsen is in talks with SonicBlue's ReplayTV and other companies that make similar PVRs with different proprietary systems.
Although it has announced the technological capabilities to monintor TiVo viewing behavior, Nielsen has not yet set a date for actually
'Cracked a big nut'
"We've cracked a big nut with TiVo, but we have quite a way to go," said Ms. Elliot, who explained that despite the low level of PVRs in use at present, their future proliferation raises revolutionary issues for the media-monitoring firm and its broadcast, cable TV, ad agency and marketer clients.
"Through all the 20 years we've been measuring cable," she said, "we've worked closely with set-top manufacturers, satellite services and others to develop workable monitoring systems, and we expect to do the same with this new technology.
What to capture?
"We have been discussing the next step with our clients," Ms. Elliot said, "because they need to define what they want reported. What exactly are we capturing from TiVo? For instance, right now with traditional VCRs, we have automatically credited the program as it was recorded in the home. That amount of the VCR recording goes into our initial rating. But with TiVo we can capture everything it does but what really matters to the client? How about when an item is played back at some date in the future?"
For instance, if someone records Friends and watches it a week later, should that be added to the original ratings data for the episode or counted in some other fashion?
Ad zapping as a metric?
Adding some spice to the debate is TiVo's ability to zap comercials. Will zapping be monitored and reported as a new metric?
Mr. Elliot noted that ad zapping "will probably be a very high level interest to many of our clients" ad discussions proceed but she said the company had not yet determined how to handle such data.
"The time-shifting could change the definition of how we report our ratings now," said another Nielson spokesman. "That's why we really need to make sure our clients -- or the majority of our clients -- are in agreement with us on how best to report it."