Marginal Approach to Ad-budget: - In this schema advertisement budget is decided on the basis of marginal costs and marginal revenue of advertising. Marginal cost here signifies increment in advertising spending. Marginal revenue signifies increment revenue because of increase in advertising spending. Acc to this approach the firm must increase advertising spending if marginal revenue is more than marginal cost. The marginal cost and marginal revenue must be equal be equal in determining the optimum level of advertising. Any further spending subsequent to the level at which incremental revenue will be unprofitable.