For all their official production measurements, OPEC uses an average
of estimates from six «secondary sources», namely the International Energy Agency (IEA), the oil - pricing agencies Platts and Argus, the U.S. Energy Information Administration (EIA), the oil consultancy Cambridge Energy Research Associates (CERA) and the
industry newsletter Petroleum Intelligence Weekly, as an impartial
adjudicator as to whether their output quotas and production cuts are being met, to resolve any potential disputes that could arise if each member reported their own figures.