Change orders occur frequently in most construction projects. Changes occur not only because of errors and omissions, but also for other reasons such as scope of work changes, or changes because of unforeseen conditions encountered on the site; a problem which is very common in most heavy construction projects. Several studies have attempted to quantify the impact of change orders on the project cost. Almost all of the studies in this area were sponsored by contractors' organizations, where

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... istical model used to quantify the impact of the change orders on the project cost was based on data supplied by the contractors; a situation that lead to owner-contractor disagreements related to the quantification method used. Also, resulting change order models didn't rely on the actual plans, specs, daily productivity and changes of the project; rather they relied on the reply of the contractor filling survey. The study addresses the need for a statistical model to quantify the increase of the contract price due to change orders from verifiable site data such as owner's daily reports, change orders, drawing, and specifications. A model is developed and validated to quantify the percent increase in the contract price due to the change orders. This model will provide the owner with an estimate of the cost of the changed work, where it can be used for forward pricing or retrospective pricing of the change orders