Malcolm Turnbull has declined an invitation for a fourth election debate issued by Bill Shorten. Which means for the first time, none of the election debates have been carried by a free-to-air commercial TV network.

Last election, both Nine and Seven carried a Sunday night debate at the Press Club live to viewers. Both carried some form of live audience feedback mechanism — Seven let viewers download an app, while Nine’s airing, on GEM, aggregated the views of 100 undecided voters to display “the worm”.

But the TV networks stayed away this time. Seven news director Craig McPherson told Crikey this morning the network wasn’t sure the viewer interest was there.

“We certainly thought long and hard about the mainstream appetite for election debates and decided it wasn’t great. Given the length of this campaign there is an over supply of political fare and the demand by the greater public, outside our normal news domains, just isn’t there.

“[We were] more inclined to focus our energies on the extensive campaign coverage and analysis across Sunrise and 6pm news.”

Meanwhile, it’s hard to gauge exactly how many people tuned into Friday night’s “innovative” Facebook debate, hosted by news.com.au. The video feed says it had 801,000 viewers, which is comparable with how with how many people watch the TV current affairs shows every night. But a Facebook “view” isn’t a viewer — Facebook collates as a view anyone who’s scrolled past its videos on their feed, even if they have the sound turned off. And Facebook views are a cumulative count; TV ratings are an average viewership.

On Sky News, which also aired the news.com.au debate, it had 33,1000 viewers.