Engineers have the responsibility to create projects having attractive returns on investment and to create economically sound designs — designs that produce high-quality, competitively priced products. This requires the technical and economic study of many different options. When doing studies, the design is usually not well defined, so one will often use factor methods for capital estimating. With these methods, one first determines the purchase cost of the equipment and multiplies that by a factor to determine the capital cost of a process or plant. The accuracy of factored estimates is usually good enough to produce high-quality decisions.