**An expression of **uncertainty. The likelihood that the true value will be contained with a given interval. The 95% confidence level is conventional but arbitrary; ideally, one would choose a limit that balances costs and benefits, but that is seldom easy to do. In forecasting, the term *confidence interval* refers to the uncertainty associated with the estimate of the parameter of a model, while the term *prediction interval* refers to the uncertainty of a forecast. Confidence intervals play a role in judgmental bootstrapping and econometric models by allowing one to assess the uncertainty for an estimated relationship (such as price elasticity). This, in turn, might indicate the need for more information or for the development of contingency plans.