Bidding Models—Symmetry and State of Information


Several competitive bidding models since the late 1960's have been founded, criticized, and even rejected, based on incorrectly stated arguments concerning the apparent symmetry of the competitive positions of the prospective bidders. The proliferation of these arguments has led to confusion about the validity of the proposed models. This paper: (1) Illustrates the correct use of symmetry in competitive bidding as a function of available information and control; (2) explains the differences among nonsymmetric states of information that lead to apparent symmetry in the case of only two competitors; (3) presents and explains the assumptions that lead to Friedman's general bidding model; (4) proves the probabilistic validity of Friedman's model by using correctly stated arguments of symmetry; and (5) provides the foundations for understanding the limitations of other models.


Photios G. Ioannou

Civil & Environmental Engineering Department

University of Michigan

Ann Arbor, Michigan 48109-2125, U.S.A.



Bidding models, bids, competitive bidding, cost estimates, markup, low bid, probability theory, statistical analysis, symmetry of Information.


Ioannou, P.G., "Bidding Models—Symmetry and State of Information," Journal of Construction Engineering and Management, ASCE, Vol. 114, No. 2, 214-232, June 1988.