Facebook discloses new measurement errors, continues to hone its math

Math is hard, even for Facebook. And it’s getting harder to trust Facebook’s math, even as the social network fine-tunes its calculations. For the third time since September, Facebook is disclosing new measurement errors. The two new errors affected the reaction counts Facebook reports on Pages’ Live videos, as well as the engagement figures Facebook reports for off-Facebook links; the latter link engagement metrics were recently used in investigations by BuzzFeed and The New York Times into fake news articles’ performance on Facebook.