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Google CEO Sundar Pichai.
Google AMP pages are designed to speed up page load times on the mobile web, by stripping out a lot of the design and advertising elements that slow the average website down. Google AMP pages are signposted in its search results pages with a small lightning bolt image.
Oliveira found that a single visitor to a website, running on Google's AMP can be reported as four unique visitors.
Also, when a visitor navigates away from an AMP page to another page in the same website, but not on Google's mobile page format, the analytics software registers a person leaving the website, Oliveira said.
The issue occurs because Google is serving a publisher's content on AMP pages, rather than the publisher itself, which creates a problem with analytics services. The cookies on the AMP pages and publisher pages don't match up, creating duplicate users within analytics software - increasing bounce rates and unique visitor numbers.
Oliveira conducted his tests using Google Analytics but told Business Insider any analytics provider would be affected by the bug.
A Google spokesperson pointed us to a tweet from Malte Ubl, Google's creator and tech lead of the AMP project, who said the company was aware of the issue, but he added there is "not an easy fix."
According to the website profiling tool SimilarTech, more than 700,000 websites use Google AMP.
SimilarTech marketing director Daniel Buchuk told Business Insider the Google AMP measurement bug "is a real issue that needs to be taken seriously," especially among publishers and marketers who rely on the data to make editorial and advertising decisions.
He added: "I'm surprised Google's team hasn't been quicker to react to this problem to find a solution that affects so many publishers around the world. Adobe Analytics revealed earlier this year that AMP accounts for 7% of traffic to US publishers and The Guardian disclosed earlier this week that they're getting 60% of its Google mobile traffic from AMP. It would be interesting to know how accurate these figures are now that the bug has been acknowledged."
Google's AMP launched in February 2016 after Facebook launched its own rapidly loading page format, Instant Articles, which has also suffered its own metrics issues. In December 2016, Facebook admitted a bug had caused comScore to undercount Instant Articles traffic from iPhone users.
@bastanzio @christian_wilde this is essentially correct. Should be documented somewhere as a known issue.
- Malte Ubl (@cramforce) March 2, 2017
