NEW YORK: Up to one in five viewers of US television's most popular programs skip or fast-forward through the commercials when watched via a digital video recorder, reveals the latest data from Nielsen Media Research.

Week commencing September 24 saw the debut of most networks' populist fall shows - traditionally a closely watched period. But never more so than this year, with the advent of data collected from viewers' digital video recorders.

The latest numbers include not only commercials viewed 'live' but also those watched (or not) via DVRs during the three days after transmission.

Although it is too early to draw firm and lasting conclusions from the data, neither networks nor marketers will be pleased with the outcome - which can only fuel concerns about the declining efficacy of TV advertising.

However, there is an interesting dichotomy in ad-skipping habits, in that they appear to vary - not only from show to show but also whether the program is watched 'live' or later via DVR.

For example, one of CBS' top-rated shows, Survivor: China, saw 19.3% of the audience who watched the show 'live' (around 5.16 million people aged 18- 49) skipping the commercials.

But if viewership is expanded to include people watching up to three days after transmission, the total audience level rises to 6.51 million - of whom 5.23 million watched the commercials.

Other top shows on CBS and rival networks experienced a lesser drop in commercial viewing, varying between 10% and 20%

Steve Sternberg, evp of audience analysis at agency media network Magna Global observes that, in general, program ratings that include three days of playbacks are 16% higher for the 18-49 age group.

Data sourced from Wall Street Journal Online. additional content by WARC staff