During the course of design development, a “rolling” estlmate will be maintained to keep the design team aware of the budget at all times.An estimate is accurate if the observed time/cost falls within your tolerances around the estimate. As noted elsewhere, these tolerances may be more or less strict and this will impact which part of your distribution curve will be used for the estimate.To approximate is to calculate the value of something based on informed knowledge. … As a verb, approximate means “to estimate.” Unlike the word guess, approximate implies the use of a logical or mathematical method.

The purpose of cost estimation is to predict the quantity, cost, and price of the resources required to complete a job within the project scope. Cost estimates are used to bid on new business from prospective clients and to inform your job and budget planning process. Estimating is done at the beginning of new projects to arrive at an original cost estimate, but should be frequently reviewed and updated as new information becomes available or conditions change.