1 OPEC announcements and their effects on crude oil prices

We investigate evidence on the effects of OPEC announcements on world oil prices by examining announcements from both official conferences and ministerial meetings on major international crudes, including the key benchmarks and several other heavy and light grades. With data from 1982 to 2008, we use event study methodology and find differentiation in the magnitude and significance of market responses to OPEC quota decisions under different price bands. We also find some (weak) evidence of differentiation between light and heavy crude grades