The construction cost estimate, often expressed as an absolute cost, leads to misunderstanding between client, designers, and builders. If estimates are to be used as adequate cost indicators, their probabilistic nature must be recognized and they must be expressed not as absolute numbers but in terms of a number with some indication of the magnitude of the risk that that number may be expected to change by some stated amount. In order to develop this new type of estimate, a model is constructed that assigns a probability distribution to each cost component of the project and ends up with a probability distribution of the total cost of the project rather than a single answer. This bracketing of the cost provides a better in-depth look at the current knowledge of the project cost than does the traditional estimate. (Author)