According to TiVo’s analysis, the 7 May episode of hospital drama Grey’s Anatomy had the potential to deliver a commercial audience of 17 rating points through time-shifted viewing.

But commercials running during the programme only received a 2.7 rating, said Todd Juenger, vice president and general manager of TiVo Audience Research & Measurement. “Simply put, 14.3 ratings points worth of audience or 84% of available viewers during time-shifted viewing were lost to fast-forwarding during commercials,” he said.

Unveiling the new service, Juenger said: “Audiences for television programmes have always been defined by the entire programme block, including all the content, commercials and promotion elements. While we continue to offer that, in the world of DVR viewing, it’s no longer sufficient.”

Other features recently added to the Stop Watch service include the Commercial Viewership Index, which measures the size of the commercial audience relative to the surrounding programme based on 15-minute intervals rather than the total programme block. Households Using Television charts, meanwhile, show how many subscribers in total are watching television at any given point in time, either live or time-shifted.

TiVo’s ratings are produced using second-by-second clickstream data sourced daily from a random, anonymous sample of 250,000 subscribers. The company plans to increase the sample size to 300,000 by September 2009.