LONDON: The increasingly widespread use of virtual private networks (VPNs) to access the internet, especially in developing markets, poses a threat to digital publishers' collection of data that can be used to target advertising.

Research firm GlobalWebIndex surveyed 170,000 individuals spread across 32 countries for its new report, The Missing Billion, which explores how passive web analytics have skewed understanding of the global internet population. It argues that trends in VPN usage, device sharing and mobile-only access mean that hundreds of millions of internet users are effectively invisible in traditional internet studies.

Its own research suggests that there are around 410m people worldwide using various software and technology to help them mask their true location and to remain anonymous while online.

In part this is about overcoming restrictions imposed by governments and media companies, whether China's ban on social media sites like Facebook or Twitter or US sites limiting access to TV shows to US users.

The survey revealed that 50% of the total simply wanted access to better content while 28% were looking to access news and social networking sites.

"It's definitely an issue," agreed Steve Carrod, co-owner and director of consulting at Digital Media Performance Group. "A major international broadcast client of ours sees 90% of traffic to its Chinese service supposedly come from the US due to VPN use," he told DigiDay.

"It affects their ability to personalise content," he continued. "It also skews conversion data for things like subscriptions, email signups, or any key conversion point."

In Indonesia, the proportion of online consumers using a VPN stands at over 40%, while the figure is over 30% in other major emerging markets including Brazil, China, Mexico, India and Turkey.

The report further estimated that the prevalence of device sharing in emerging markets – for example, 38% of Brazilian users only go online with a shared device – had resulted in 417m internet users not being counted.

"International markets are a missed opportunity for some companies," said Jason Mander, head of trends at GlobalWebIndex. 

"This issue with Web analytics might leave some to believe America is dominant in terms of Internet use, that foreign markets are still 'emerging' on the Web. In fact, they have huge digital populations and a hunger for quality content."

Data sourced from GlobalWebIndex, DigiDay; additional content by Warc staff