Uncertainty may be defined as imperfect knowledge. Uncertainty and risk are terms that are often related. Some economists distinguish between risk and uncertainty in terms of uncertainty representing things that we cannot measure and risk representing things that we can measure. If a farmer agrees to sell this season’s crop to a retailer at $1 per kilogram, the farmer has minimised his uncertainty, he knows exactly what price he will get. However, the farmer has not reduced his risk, as the market price for his crop might be $2 per kilogram later in the season. See also Risk.