| 摘要 | This paper examines the structural characteristics of the world crude oil supply market by deriving theoretical frameworks and conducting empirical evaluation. To construct the theoretical framework, the profit-maximization model is applied to the competitive supply market, such as Non-OPEC suppliers, while cartel model is applied to the non-competitive supply market, such as OPEC suppliers. The separate analysis on supply market by competitiveness shows that crude oil supply is determined by market economy for Non-OPEC and political economy for OPEC. Therefore, this paper confirms that the analysis on oil prices is difficult as long as the market economy is simply applied to the analysis but strongly disagrees with the non-economic view that oil-price analysis is difficult by the undescribable factors outside of the crude oil market.
From the previous researches on the crude oil supply market, the distinguished research-attempt by this paper is to find how the behavior of crude oil suppliers are different by their spare capacity of oil-supplying. Although the term, ��spare capacity�� is usually referred to OPEC not to Non-OPEC since Non-OPEC supply as much as they can for any sale-profits, this paper also applies the term to Non- OPEC since its mathematical meaning of the supplying-capable amount of oil is reasonably related to Non-OPEC too. Using this extensive application under the assumption of competitive supply market where the supplier have the profit-maximizing incentive, this paper can derive the upward-sloping curve of Non-OPEC supply function .
However, the OPEC supply function is not simply determined by the profit-maximizing model because OPEC is not competitive. In other words, OPEC certainly considers the organizational economic incentive but the incentive is more based on the member's political economy than on individual competitive market economy. The member's political economy can be explained by a way of cartelization, so that this paper provides qualitative analysis instead of mathematical framework analysis. In addition, OPEC's non-competitive supply behavior is explained by the applied backward-bending curve initially suggested by Krugman's critical writing on crude oil market in his web-site. Krugman's argument, based on the general backward-bending curve of OPEC supply, is that the backward- bended supply changes the direction to positive-sloping supply if the oil price progresses to high level.
After the theoretical analysis on the crude oil supply market, this paper conducts the empirical evaluation for the argument that crude oil supply changes by the spare capacity. Using the most-cited crude oil supply model that was suggested by Griffin (1985), this paper estimates the price elasticity of supply in the world crude oil market for three sample periods, 1992 - 2006, 1992 - 2002, 2002 - 2006. The estimated elasticities those for the sample periods, however, are statistically insignificant except for the sample period, 2003 - 2006 like most of the previous empirical studies on estimating crude oil supply elasticity.
Concerning of the statistical insignificant supply elasticity, this paper focuses on the following three research topics. The first is that estimating the crude oil supply elasticity is for the separate group or individual country rather than for the entire world since the individual supply characteristics are offset by the aggregated supply elasticity. The second is that we need to focus on the negative elasticity for the period, 1992 - 2002 since the supply elasticity in common markets is positive. This negative elasticity partially shows that the crude oil supply is related to target revenue theory with the implication of backward-bending supply curve. The last is that the supply elasticity for the period 2003 - 2006 is estimated statistically significant, when the spare capacity structurally decreased.
For the first and second topic, this paper estimates supply elasticity of individual oil-supplying country under the three sample periods. The results are that the number of significantly estimated elasticity increase when the elasticity is estimated by individual country and the OPEC country is more likely to have negative elasticity than Non-OPEC, which implies that OPEC's supply is partially explained by the target revenue theory accompanying the backward-bending supply curve. Also, the negative supply elasticity of OPEC suggests that the target revenue theory is best applied to explain the OPEC's supply behavior for the normal period time when the price changes are normal. For the last research topic, this paper estimates and compare the supply elasticities for two comparative periods, (1) 1992 - 2002 vs. 2003 vs. 2006 (2) Jan. 2003 - Sep. 2004 vs. Oct. 2004 - Aug. 2006. The reason to compare the periods, Jan. 2003 - Sep. 2004 vs Oct. 2004 - Aug. 2006, is that spare capacity structurally decreases at Sep 2004 according to the IEA data. The result shows that supply elasticity is lower for the latter period, which implies that supply slope becomes steeper for the period when the spare capacity structurally decreases.
In conclusion, the summary of the empirical results are as the followings. Although the world oil supply elasticities estimated in most of previous studies were statistically insignificant, this paper can obtain statistically significant supply elasticity when we estimate by individual base not by the aggregated whole world base. In addition, I confirm that Non-OPEC supply elasticity has positive slope as I derive the upward-sloping supply function of Non-OPEC supply in the theoretical part. For the case of OPEC supply, this paper partially confirms that OPEC supply is based on the target revenue theory and has backward-bending. However, the further study should be conducted to confirm the OPEC's supply behavior and functional shape.
Finally, I would like to suggest an policy implication based on the theoretical and empirical results on crude oil supply market. To understand the structure of crud oil supply market, the relevant policy should be made based on individual supplier rather than the whole supply market. When the government or firms are making contracts for all kinds of cooperation agrement with oil exporting country, such as FTA, resource-economy cooperation, oil-field investment contract, etc., they can be informed of the oil-exporting country's characteristics of supply behaviors by checking the supply elasticity of the country. Checking on the supply elasticity surely provides information on the supplier's oil and macro-economic policy, which is the step-stone to the success of all cooperation agrements with the oil-supplying country. |
