This study investigates the effects of commercial shocks on gross domestic product (GDP) by classifying the foreign exchange system in oil developing countries and non-oil developing countries in the period 1990-2015 using Friedman's hypothesis. The results of the research indicate that commercial shocks cause more changes in real product in countries with a fixed exchange rate regime than countries with floating exchange rate regime in non-oil developing countries that this hypothesis in oil developing countries is rejected both in fixed exchange regime and in floating exchange regime. This result is true in all countries investigated. Also, analysis of variance analysis shows that in countries with a fixed exchange rate regime (non-oil), commercial shocks have the highest percentage in explaining the volatility of GDP. The share of commercial shocks in explaining real product volatility in countries with a fixed exchange rate regime is between 51-67%. Also, in countries with a floating exchange rate regime, this amount is 1-6%. In general, the results in non-oil countries are consistent with Friedman's hypothesis, but the effects of commercial shocks on GDP, with the classification of the foreign exchange system in oil developing countries (in all three types of fixed exchange regime, managed floating, floating) don't have a certain rule and Friedman's hypothesis cannot be accepted.
