1.2.1.  Parametric Cost Estimates.

1.2.1.1.  Many construction contractors use a rule of thumb, or parametric cost estimating, to prepare their estimates. It is particularly useful when design details are not available. Government estimators often use this method to develop programming or budgetary cost estimates.

1.2.1.2.  For example, if the requirement is for a brick two-story house with a basement, the contractor might use $60/square foot (or whatever value is currently reasonable for the application) to estimate the price of the house: $60/sq ft x 2200 sq. ft = $132,000 house price (see NASA's Cost Estimating Website)

1.2.1.3.  In this example the estimate relates floor space to building cost. Once a general structural design is determined, the contractor can use this relationship to estimate the total building price or cost (i.e., plus up or down scope) - excluding the cost of land. This technique is reliable and can save both the contractor and the Government time and resources in the development of estimates and it produces results similar to that of other more detailed techniques.