Facebook reveals fresh flaws with its data Published duration 16 November 2016

image copyright Reuters image caption Facebook has twice revealed problems with its data since September

Facebook has acknowledged four new errors in the figures it shares with advertisers and publishers.

The "bugs" could cause companies to think users had spent longer reading news articles than they had done, and that more people had been exposed to non-paid posts than had been the case.

The alert comes two months after the firm revealed it had overestimated the average time users had watched videos.

But Facebook says none of the cases would have affected its fees.

Neither would all of the examples have worked in its favour.

One of the newly revealed flaws meant it was underreporting the percentage of users who had watched videos on its platform to their end.

Facebook makes more than 200 metrics about its site available to third parties.

The latest mistakes might appear relatively minor in nature, but one digital marketing expert said they undermined confidence in the social network.

"It certainly doesn't help when they keep having to restate metrics, especially when companies are buying ads based on that data," said Ian Maude, group development director at Be Heard.

"It adds to concerns that advertisers and agencies already have and underlines the argument that there should be some sort of independent third-party measurement system, which could give people a little bit more confidence in the numbers."