Facebook’s ad metric problem is becoming Zuckerberg’s headache

Mark Zuckerberg has a credibility problem. The tech mogul’s Facebook just admitted to finding more “bugs” in the way it measures ads — and once again, those bugs benefited Facebook. The social-networking giant said Wednesday it has found numerous errors in the ways it calculates how many people view its ads, artificially inflating their perceived value to advertisers and publishers. Key metrics that Facebook has exaggerated include the weekly and monthly reach of marketers’ posts, which got inflated by 33 percent and 55 percent, respectively, as the site improperly included repeat visitors in its figures. Elsewhere, Facebook admitted to exaggerating the number of full views that video ads received, as well as time spent by users reading fast-loading “Instant Articles” for publishers including The Post and the Wall Street Journal, both of which are owned by News Corp. Facebook insisted that the messed-up metrics — which followed the company’s admission in September that it had inflated its reporting of video viewing times to advertisers by as much as 80 percent — didn’t affect billing to publishers and advertisers.