Petroleum University of Technology Petroleum Business Review 2645-4726 3 3 2019 09 01 Fluctuations and Changes in Expected Rate of Return Based on Comparability and Environmental Uncertainty in Oil, Gas, and Petrochemical Firms 43 51 113683 10.22050/pbr.2019.113683 EN Mohsen Rashidi Assistant Professor, Accounting Department, Lorestan University, Khoram Abad, Iran Journal Article 2019 06 11 <span class="H5CharChar"><span>The purpose of this study is to investigate the effect of comparability and environmental uncertainty on the expected rate of return. The current study utilizes panel regression method estimator to investigate the relationship between comparability, environmental uncertainty, and the expected rate of return of 500 firm-year observations in oil, gas, and petrochemical firms listed in Iran Securities and Stock Exchanges for the period of 2009 to 2018. The results show that the comparability and uncertainty have a significant effect on the expected rate of return. In other words, the expected rate of return is a function of comparability, and it varies at different levels of comparability.</span></span> https://pbr.put.ac.ir/article_113683_06c0d42b9710ec00de1e456cb82004bf.pdf