想请教一下学经济的朋友 最近上microeconomics，上到关于perfect competition. 结论是in a long-run equilibrium, the firm’s economic profit must be zero. In this case, there is no incentive for new firms to entry or old existing firms to exit. 这个我可以理解 我是这么想的 for example, let’s say I and Kelly were both waiting tables and making $10,000 (net income) a year, but I decided to quit my job and chose to become a teacher where I can make $12,000(net income) a year. My accounting profit is $12,000, but my economic profit is $2,000. Kelly will have incentive to become a teacher as well because of the extra $2,000. However if I ended up making $10,000 as a teacher. My accounting profit is $10,000, but my economic profit is 0. Kelly won’t have the incentive to become a teacher because she might as well just be a waitress. 所以当一个公司的economic profit 是零的时候，新的公司不会想进来，旧的公司不会想退出 因为反正不开公司去别处赚钱最后收入都一样 但是我们老师，却说是accounting profit is zero! 我目瞪口呆 如果我开个公司结果accounting profit 是zero 相当于我的net income 是0 那我还要开什么公司？回家睡觉好了！ 我就有一个问题 当我们在讲perfectly competitive market 的时候 各种graph. MC, ATC, AVC, MR, 我们所求出的profit都是economic profit吧？如果是这样的话，那请问公司是怎样将opportunity cost 算进去ATC 或者是分配到AVC or AFC. 请牛人advise! ---发自Huaren 官方 iOS APP
想请教一下学经济的朋友 最近上microeconomics，上到关于perfect competition. 结论是in a long-run equilibrium, the firm’s economic profit must be zero. In this case, there is no incentive for new firms to entry or old existing firms to exit. 这个我可以理解 我是这么想的 for example, let’s say I and Kelly were both waiting tables and making $10,000 (net income) a year, but I decided to quit my job and chose to become a teacher where I can make $12,000(net income) a year. My accounting profit is $12,000, but my economic profit is $2,000. Kelly will have incentive to become a teacher as well because of the extra $2,000. However if I ended up making $10,000 as a teacher. My accounting profit is $10,000, but my economic profit is 0. Kelly won’t have the incentive to become a teacher because she might as well just be a waitress. 所以当一个公司的economic profit 是零的时候，新的公司不会想进来，旧的公司不会想退出 因为反正不开公司去别处赚钱最后收入都一样 但是我们老师，却说是accounting profit is zero! 我目瞪口呆 如果我开个公司结果accounting profit 是zero 相当于我的net income 是0 那我还要开什么公司？回家睡觉好了！ 我就有一个问题 当我们在讲perfectly competitive market 的时候 各种graph. MC, ATC, AVC, MR, 我们所求出的profit都是economic profit吧？如果是这样的话，那请问公司是怎样将opportunity cost 算进去ATC 或者是分配到AVC or AFC. 请牛人advise! ---发自Huaren 官方 iOS APP serenatsai 发表于 10/18/2019 1:22:51 AM
回复9楼无声中沉寂的帖子 那你如何解释 in a long run 公司的MR=ATC. 如果是accounting profit 的话 那么现在accounting profit =0. Economic profit is negative 但实际上in a long run economic profit 一定是zero 所以accounting profit 不可能是0. ---发自Huaren 官方 iOS APP
完全竞争市场是假设的理想情况。 与之类似，中学物理里牛顿定律同样假设“无阻力”情况下物体可以一直匀速直线运动，但我们知道真实物理世界不可能完全无阻力。 经济学里的完全竞争假设也是类似的“无阻力”假设，真实经济当中肯定有各种各样market frictions，完全竞争根本不存在的，各行各业都有行业壁垒，极端情况变成垄断行业。那为什么要这么假设，因为完全竞争市场提供了一个分析更复杂问题的起点，可以加上各种market frictions，研究这种情况下市场会怎样，比如各种垄断模型。 ----当然了，一般老师不会讲这么透，很多老师照本宣科自己也没多想。
完全竞争市场profit就是0。 完全竞争市场里面其实还隐含完全同质化，完全没有entry/exit barrier，没有信息不对称，没有任何别的market friction。
你说的那个图表上 都是accounting profit, 所谓的economic profit只有跟机会成本联结的时候才会被提及。