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This paper develops a New Keynesian dynamic stochastic general equilibrium (DSDE) model to study Iran's economy. The model considers the dependence of Iran's economy to oil exports. Oil sector and oil export revenues have been modeled as a separate sector and one of the government budget resources, respectively. In this model, like in other New Keynesian DSGE models, firms face nominal rigidities and the intermediate-good sector is monopolistically competitive. Four shocks (productivity, oil revenues, money growth rate and government expenditure) have been introduced as the sources of volatility. The findings show that business cycle moments generated by the model and those of actual statistics from the economy are closely related. The model produces more volatile private investment and less volatile private consumption than non-oil output. Impulse response functions of shocks show that non-oil output increases in response to productivity, oil revenues, money growth rate and government expenditure shocks. Although non-oil output increases in response to government expenditures shocks, crowding- out effect of these expenditures causes output to decrease after some periods.

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The objective of this paper is to investigate the validity of Wagner’s law and the Keynesian view with regards to the relationship between the non-oil gross domestic product and the public sector size for the Iranian economy during the period of 1967-2007. Time series analysis techniques have been used which include unit root tests, cointegration tests and Hsiao causality test. The findings indicate that Wagner’s Law is confirmed in both the short-run and the long-run; whereas the Keynesian view is approved only in the short-run for Iran.