Timely and accurate oil production data is critical for understanding both the short-term oil market and for global energy balances. In the absence of reliable official data from many key oil producing countries, oil market analysts rely on a range of independent estimates, including those from media and energy organizations and consultants. The OPEC Secretariat uses six of these organizations which it terms ‘secondary sources’: the International Energy Agency, the Energy Information Administration, Platts, Argus, Energy Intelligence and HIS-CERA. Other ‘third-party’ organizations that monitor oil production include, inter-alia, Bloomberg, Reuters, the Middle East Energy Survey (MEES) and Energy Aspects. Many of the current data providers, notably media organizations, tend to focus on month-end snapshots, leaving larger energy organizations and consulting firms to provide more accurate data on energy balances, which are revised over time.