NEW YORK: Nielsen, the research and measurement firm, has updated its total audience metric to better reflect changes in TV viewing habits with the result that audience levels have increased by around 10%.

In what could be a significant boost for TV networks, who have frequently complained that Nielsen ratings do not properly measure online audiences, the new metric includes viewers of online video sites, such as Netflix and YouTube, as well as traditional channels, and captures data across multiple devices.

In addition, Nielsen will extend the period it counts viewers from the current standard of three or seven days to a full 35 days, the Financial Times reported.

According to the report, Nielsen has already released this total audience data to TV networks, so they can review it, before the new ratings are rolled out to ad buyers by the start of the autumn TV season.

Tests have shown that the new measurement increased viewership across all TV shows by 10% on average, but one broadcast drama saw a 23% increase in viewers, rising even higher for the most popular shows.

Separately, Nielsen took part in a media conference in Las Vegas last week and provided viewership figures for a select number of streamed shows.

As reported by the Wall Street Journal, Nielsen calculated that 6.7m people tuned in to the fourth season of "Orange is the New Black" on Netflix from June 17 to June 19. Over the same period, 5.9m watched the show's second season.

Nielsen also provided data for "Seinfeld" on Hulu and revealed that reruns of the comedy series were watched by 706,000 US viewers in the first five days that they were made available.

Elsewhere, Nielsen said that just over half (52%) of US households now have some sort of subscription to a video streaming service, up from around 40% two years ago. In addition, 16% of viewers who watch a show on Netflix also watch it on traditional TV.

Data sourced from Financial Times, Wall Street Journal; additional content by Warc staff