Figure 3, which is based on Pogue and Sgontz (1989), provides a simple illustration for just two
groups. The first group are normal alcohol-level consumers whose consumption involves no external
costs. The second group are excessive-level consumers where consumption involves external
costs. Following the format of Figures 1 and 2, in a competitive market, the demand curves for a
representative consumer in each group is represented by an MPBi curve, for i = n and e for normal
and excessive consumers, respectively. Assume for simplicity, and with no loss of generality, a perfectly
elastic supply curve equal to MPC = MSC. Then, in a market or private choice situation each
group chooses quantity Qi. In the case of the normal-level consumption group, as in Figure 1, there
are no external costs so that MSB = MSC, and the chosen Qn is efficient for both these individuals
and society. In contrast, in the case of the excessive consumption group, there is a positive external
cost and the MSB = MPB ) MEC. Then, as in Figure 2, the excessive consumption group consume
too much at Qe, with a social optimum at Q* and a potential efficiency gain of area ‘‘b + c ’’.
Suppose a tax at rate T is imposed on producers for all alcohol consumed domestically. This
forces the supply function upwards with price rising by T to P¢. Both sets of consumers reduce consumption
to Qi¢. The tax reduces some of the external costs of excessive drinking with an efficiency
gain of area ‘‘c’’, but at the same time the reduced consumption for the normal group causes a loss
of efficiency of area ‘‘a’’.
Figure 3, which is based on Pogue and Sgontz (1989), provides a simple illustration for just twogroups. The first group are normal alcohol-level consumers whose consumption involves no externalcosts. The second group are excessive-level consumers where consumption involves externalcosts. Following the format of Figures 1 and 2, in a competitive market, the demand curves for arepresentative consumer in each group is represented by an MPBi curve, for i = n and e for normaland excessive consumers, respectively. Assume for simplicity, and with no loss of generality, a perfectlyelastic supply curve equal to MPC = MSC. Then, in a market or private choice situation eachgroup chooses quantity Qi. In the case of the normal-level consumption group, as in Figure 1, thereare no external costs so that MSB = MSC, and the chosen Qn is efficient for both these individualsand society. In contrast, in the case of the excessive consumption group, there is a positive externalcost and the MSB = MPB ) MEC. Then, as in Figure 2, the excessive consumption group consumetoo much at Qe, with a social optimum at Q* and a potential efficiency gain of area ‘‘b + c ’’.Suppose a tax at rate T is imposed on producers for all alcohol consumed domestically. Thisforces the supply function upwards with price rising by T to P¢. Both sets of consumers reduce consumptionto Qi¢. The tax reduces some of the external costs of excessive drinking with an efficiencygain of area ‘‘c’’, but at the same time the reduced consumption for the normal group causes a lossof efficiency of area ‘‘a’’.
การแปล กรุณารอสักครู่..