Mary Jane Sudekum, Pharm.D., and Lee C. Vermeulen, M.S. Key Words: therapeutic interchange, guidelines, drug policies, drug. procedures, pharmacy and therapeutics committee, patient care, cost-effective. therapy, American College of Clinical Pharmacy, ACCP, position statement.
The law of diminishing marginal utility is similar to the law of diminishing returns which states that as the amount of one factor of production increases as all other factors of production are held the same, the marginal return (extra output gained by adding an extra unit) decreases.
Because the supply curve is increased, more of the product is bought than the efficient amount--that is, too much of the product is produced and sold. Since marginal benefit is not equal to marginal cost, a deadweight welfare loss results. This graph shows the effect of a negative externality. The red line represents society's supply curve/marginal cost curve while the black line represents the marginal cost curve that the firm or industry with the negative externality faces. The optimal production quantity is Q', but the negative externality results in production of Q*.