The changing art of measuring TV viewership

If everyone started watching "24" or "CSI" on video iPods or streamed over the Internet - instead of on TV in their living rooms - these top-rated shows would probably go the way of "Cop Rock."

That is, Jack Bauer would become the victim of, not terrorists, but bad ratings. This is because Nielsen Media Research cannot collect data about what people watch on handheld video-viewing gadgets or from PCs streaming network TV shows. While Nielsen estimates around 90% of TV viewing still happens in homes, it's this burgeoning 10% that TV networks and advertisers are desperate to delve into.

"The industry is just dehydrated for this data," says Bob Luff, Nielsen's CTO, who oversees the design of the technology used to collect and measure TV viewing habits in more than 40,000 Nielsen homes. "But how do you measure what's on a video iPod at 38,000 feet on an airplane's fold-down tray?"

The demand for this new data is changing how Nielsen collects and processes its ratings numbers, which each year drive TV advertising and programming worth $70 billion and determine what soars and bombs in show business.

Anywhere metering

Over the years, keeping up with video technology has been a challenge for Nielsen, Luff says. The company's traditional technology for tracking TV viewing involved set-top boxes - called People Meters - which recorded what channels were watched and when. This technology used physical taps and probes wired into a TV or cable box to read channel numbers or the UHF/VHF frequency of the set. Analog modems in the back of the Nielsen People Meter provided nightly phone calls to a data center where information on viewing events - every minute of TV watched, including channel changes - was deposited at 2 a.m.

The increasing complexity of home electronics, and new technologies such as time-shifted viewing via TiVo, forced Nielsen to come up with new ways to identify what people were watching, and when. Nielsen worked with TV broadcasters to invent two technologies that let its meters recognize when a show is playing, based on signals hidden in the audio. One method, called psychoacoustic encoding (see story), injects a digital time stamp and program title - or "active signature" - into the audio tracks of TV shows as they are broadcast. Another technique, called passive signatures, creates a kind of audio fingerprint for TV shows; a split-second sample of audio is digitized, creating a unique signature, which also can be recognized by metering equipment.

These two types of signatures will also allow Nielsen to tap into the viewing habits of mobile video users, or even those watching regular TV outside the home.

Click to see: Go Meter

One gadget in the works is the Go Meter, which some Nielsen participants next year will begin to carry with them throughout the day.

"If you think [iPod] Nano, you're pretty close to what the Nielsen Go Meter will look like," Luff says. The device samples the ambient audio surrounding the user and searches for the psychoacoustic codes embedded in TV programs. Recognized signatures are logged and stored in flash memory in the Go Meter. The gadget's docking station - similar to a PDA or iPod cradle - recharges it at night and uploads the day's codes during the 2 a.m. data deluge via a modem.