Economic models focus on prices that announce a cost for one unit. Often prices assigning a cost for multiple units are chosen. For either, any quantity can be purchased at a constant per unit price. I incorporate the experimental phenomenon of mathematical miscalculations to explain the use of...

The standard vertical-product-differentiation model assumes that quality and quantity are independent choices. That is, the choice of quality is separated from the decision of the number of units to produce. For certain products this is not appropriate. This note presents an extension to the...