In 2011, El Salvador made policy reforms to a national subsidy on propane gas, causing widespread public disaffection and a series of strikes by distributor companies. The World Bank and Global Pulse collaborated on a research project analysing content and sentiment of tweets in order to better understand public opinion around the reforms. The study demonstrated that public opinion as expressed in social media could complement and potentially replace household survey data if none were available. While a decline in negative sentiment was observed around several issues, including the gas distributor strikes, household survey data from the same period showed an increase in positive sentiment on the reform. This discrepancy showed that analysing social media could help reveal unexpected impacts of issues and events related to policy. In the case of the fuel reform, the research findings showed that the distributor strikes might have contributed to changes in public perception more than previously acknowledged.