In an unusual move, the main broadcast networks in America have teamed up to reveal research showing that PVR owners watch more TV - and, crucially for the free-to-air terrestrial broadcasters, more adverts.

Citing electronic measurement methods, the networks said that households with a PVR watch 12% more TV than households without one (5.7 hours of TV are watched per day in PVR-equipped homes compared to 5.1 hours in homes without the devices, according to the research). Also, PVR owners are "exposed to a greater number of commercial impressions."

Specific PVR-related statistics were also unveiled. Citing a Nielsen Media Research study in seven major US markets (Raleigh, NC; Charlotte, NC; Tampa, FL; Orlando, FL; Denver, CO; Houston, TX; Austin, TX), the networks said that audiences for primetime programmes increased by an average of 4% when PVR usage was taken into account. Another study conducted by the networks themselves claimed that 58% of PVR users pay attention to ads even while fast-forwarding, and 53% of PVR users "have gone back to watch commercials they mistakenly skipped."

PVR take-up in America is currently estimated at 8% of homes, equating to around 11.4m viewers. That number is expected to grow to 39% of homes by 2010.