A stress test is a “what if” scenario that takes the world as given but assumes a major change in one or more variables in order to see what effect this would have on various indicators. For instance, for an economy, the impact on growth, inflation, and external debt of a huge change in oil prices could be considered. Stress tests are particularly useful for financial institutions: for instance, an individual entity might consider the impact on net worth of a sharp movement in financial market prices, in order to help determine the appropriate level of capital to hold.