Suppose that we are fitting a straight line and we desire to make the variance of A as small as possible. Restricting ourselves to an even number of experimental points, where should we place these points so as to minimize V(β̂₁)? Use the design called for in this exercise with great caution because, even though it minimizes V(β̂₁), it has some undesirable properties; for example, see Myers and Montgomery (1995). Only if you are very sure the true functional relationship is linear should you consider using this design.