Valuation, represented by the red curve, means the value buyers put on a resource. The cash value buyers put on a resource depends on its scarcity or availability. Mathematically, valuation is the area under a curve on the graph (in math terms, the integral) of unit price verses quantity. Merkato uses this curve to determine the actual bids to be placed. If the red curve is not visible in a valuation graph it is under the green curve—it is exactly the same curve.