Nearly 160 million people are visiting but not 'actively using' Twitter - a huge audience Twitter should be shouting about more

Twitter is doing itself a huge disservice by using its monthly active user figure as the main metric to illustrate its growth.

Twitter missed analyst's estimates for user growth in its fourth quarter, reporting 288 million monthly active users, short of the 292 million expected. Its stock was still up as Twitter beat estimates on revenue, but that didn't prevent swathes of negative headlines about Twitter user growth stagnating.

But here's a number that could turn those headlines around. A new report from market research company GlobalWebIndex estimates that 157.3 million people across the world visit, but are not "actively" using, Twitter. GlobalWebIndex came to its (weighted) figure by polling 41,983 internet users, aged 16-64-years-old, from 32 countries, online in December.

Yes, this is a poll, not actual usage data. But it's perhaps more interesting than usage data: 160 million people identify themselves as Twitter visitors, but not Twitter users. They're the great uncounted.

Twitter CEO Dick Costolo has talked about logged out users in earnings calls previously. But it has been difficult to quantify how many people Twitter reaches who are not actual Twitter users. And there is confusion in the ad market as to the size and value of a Twitter reader who isn't a Twitter user. So having an actual number is a good peg for Twitter to hang its hat on.

Twitter itself claims that Twitter.com has 500 million unique visitors each month who don't log in. But GlobalWebIndex's poll (which it says represents 90% of the global internet audience) is a measure of people who actually identify themselves as Twitter visitors. It's the social media equivalent of people who say they are Guardian readers, but don't realize they actually also spend most of their time visiting BuzzFeed, Yahoo News and International Business Times:

Put it another way: 7% of internet users who don't have a Twitter account still visit the site, if GlobalWebIndex's poll is to be taken at face value. And Twitter has 1.5 times as many visitors as active users. Twitter also has more visitors than active users in all 32 countries GlobalWebIndex surveyed.

GlobalWebIndex believes the best measure of actual engagement, therefore, with Twitter is its combined visitor total - 459 million.

That would close the gap a little on Facebook (although Facebook is still way ahead with 1.39 billion monthly active users.) Crucially, the research company points out, visitors to Twitter who are not signed up are not particularly disadvantaged -which is the complete opposite of Facebook, where being logged in is pretty much essential.

And it's worth mentioning that people don't need to be signed up or logged in order to sell advertising and make money from advertising: It's how the majority of digital media works. Twitter is the place people go to discover breaking news - from huge global events, to what their friends are up to right this second - if it were a digital media company, it would be huge. MailOnline, the biggest global English language news website, reached 199.4 million monthly unique visitors, according to comScore.

Digging into the report, there's another really interesting nugget about Twitter's global visitor numbers: Fast-growth, developing countries are the countries where non registered users are most likely to be visitors: Saudi Arabia, the Philippines, and Turkey.

If Twitter were to use its global total visitor number, rather than continuing to use monthly active users as its key metric, the company would begin to break down the perception that it's just a niche platform. It might be niche to use, and many people may not see a reason to tweet themselves, many others find reason to visit, read embed tweets or just generally come across Twitter.

And perhaps it soon will. Twitter has recently made two big strides in the logged-out audience area:

• Earlier this week Twitter announced plans to sell ads in other apps and websites, by syndicating promoted tweets, initially with Yahoo Japan and Flipboard.
• Twitter also struck a new deal with Google to make tweets more searchable online.