OPEC members’ own versions of their oil output were for years greeted with such scepticism that the group resorted to publishing what others thought they were producing. That gave rise to a mini-industry of OPEC watchers, tapping secretive sources to track every barrel. Output was hotly contested when the group squabbled over member quotas, which have since been abandoned. But on Monday, OPEC issued a set of production figures as reported to its Vienna Secretariat by member-countries, without any countries missing from the total for the first time in months. These also showed the difference between OPEC output based on member-countries’ own submissions, and that provided by OPEC’s list of secondary sources, which include consultants and industry media, to be narrowing. “I can see some countries trying to address these problems and publish better data,” said an oil market expert working for a European government. “But […]