 The descriptive study of the "adaptive toolbox" is done by observation and experiment, the prescriptive study of the ecological rationality requires mathematical analysis and computer simulation.Heuristics – such as the recognition heuristic, the take-the-best heuristic, and fast-and-frugal trees – have been shown to be effective in predictions, particularly in situations of uncertainty.It is often said that heuristics trade accuracy for effort but this is only the case in situations of risk.