In this paper, we consider the relative efficiency of unit taxation and ad valorem taxation in terms of welfare implications in different imperfectly competitive markets. Under the assumption that these two taxations can produce the same total output in equilibrium, which is also used by Anderson (2001), we show that ad valorem taxation is always welfare superior to unit taxation under full nationalisation, full privatisation, and partial privatisation.

In the standard leader-follower duopoly models with otherwise symmetric firms, the market outcome and total welfare are the same whichever firm is the leader. This paper studies and compares total welfare in a sequential-move mixed duopoly when either the public firm or the private firm acts as the leader. It is found that the fact that which firm is the leader affects total welfare and that whether firms compete in quantity or price also affects the optimal choice of market leader.