Share prices for Facebook have gone down before trading closed for the weekend after it was revealed that a calculation error had gone unchecked for two years.

The error stems from the average viewing times Facebook users spent to watch videos posted on the platform

By not calculating shorter views and those who totally ignored that video, the average viewing time for videos has been inflated by up to 80 percent according to some firms.

Facebook has responded by confirming the error and says it had been rectified.

"We recently discovered an error in the way we calculate one of our video metrics.

"This error has been fixed, it did not impact billing, and we have notified our partners both through our product dashboard via sales and publisher outreach."

While this may not be of particular concern of the average user, advertisers depend on such information to make crucial decisions when allocating advertising revenue over several medium.