Factor Markets
AP Microeconomics Topic 5 7:56 English narration · English + 中文 subtitles burned in
Chapters
Transcript
Two workers.
两个工人。
One sews shirts in a clothing factory. The other builds cars on an assembly line.
一个在制衣厂缝衬衫，另一个在装配线上造汽车。
The second earns far more. Why?
第二个人挣得多得多。
In this unit the firm is the buyer and you are the seller, and what you are paid turns on one thing: how much extra revenue your work brings in.
为什么？ 在本单元里，企业是买方，你是卖方；你拿多少工资，取决于一件事： 你的劳动带来多少额外收入。
Let's see how that number is set.
我们来看看这个数字是怎么定出来的。
Here is the plan.
本节安排如下。
First, factor demand and the hiring rule — the one rule this whole unit is built on.
首先是要素需求和雇佣法则——整个单元都建立在这一条规则上。
Then what makes labour demand and labour supply shift.
然后是什么让劳动需求和劳动供给移动。
Then a competitive labour market, where a firm simply takes the wage the market gives it.
接着是竞争性劳动市场， 在那里企业只能接受市场给出的工资。
And last, monopsony: a town with a single employer, where the firm has real power over the wage.
最后是买方垄断： 一个镇上只有一个雇主，企业对工资拥有真正的权力。
A firm normally sells.
企业通常是卖方。
In a factor market it buys the factors of production — labour, land and capital — and households are the sellers.
在要素市场上，企业是买方——买劳动、土地和资本，而家庭是卖方。
Labour is the one the exam tests.
考试考的是劳动。
Notice where that demand comes from.
注意这种需求从哪里来。
A bakery does not want a baker for company; it wants the bread.
面包店并不是想找个面包师作伴，它要的是面包。
So factor demand is a derived demand.
所以要素需求是一种派生需求。
Two terms then carry the whole unit.
有两个术语贯穿整个单元。
Marginal revenue product is the extra revenue one more worker brings in.
边际收益产品，是多雇一个工人带来的额外收入。
Marginal factor cost is the extra cost of hiring her.
边际要素成本，是雇用她带来的额外成本。
Both come from the same marginal logic as everything else in this course: compare the marginal benefit and the marginal cost of one more worker.
两者都出自本课程处处相同的边际逻辑：比较多雇一个工人的边际收益和边际成本。
The hiring rule: hire until those two are equal.
雇佣法则就是：一直雇到这两者相等。
And marginal revenue product falls as more workers are hired, because of diminishing marginal product.
而随着雇的工人越来越多，边际收益产品会下降，因为边际产量递减。
Here is that market drawn.
这就是那个市场的图。
Workers along the bottom, the wage up the side.
横轴是工人数量，纵轴是工资。
The downward curve is labour demand — and it is the marginal revenue product curve, because that is what one more worker is worth to a firm.
向下的曲线是劳动需求——它就是边际收益产品曲线，因为那正是多一个工人对企业的价值。
The upward curve is labour supply: people offer more hours when the wage is higher.
向上的曲线是劳动供给：工资越高，人们愿意提供的工时越多。
Where they cross, the wage is settled, and so is the number of workers hired.
两条线相交的地方，工资定下来了，雇用的工人数量也定下来了。
Every firm here then takes that wage as given.
这个市场里的每家企业，都只能接受这个工资。
Now watch what the product market does to the labour market.
现在看产品市场的变化会如何影响劳动市场。
Demand for the firm's output rises, so the price of that output rises.
人们对企业产品的需求上升，于是产品价格上升。
Marginal revenue product is marginal product times price, so every worker is now worth more revenue than before.
边际收益产品等于边际产量乘以价格，所以每个工人现在带来的收入都比以前多。
The whole labour demand curve shifts right.
整条劳动需求曲线向右移动。
Follow it along the unchanged supply curve: the wage rises, and employment rises with it.
沿着没有变化的供给曲线看过去：工资上升，就业量也随之上升。
That is derived demand at work — nothing changed inside the factory.
这就是派生需求在起作用——工厂内部什么都没有改变。
So what moves the two curves?
那么什么会让这两条曲线移动？
Labour demand shifts with the output price, with worker productivity, and with the price of other inputs.
劳动需求随产品价格变化、随工人生产率变化， 也随其他投入品的价格变化。
Labour supply shifts with the number of qualified workers, with immigration, with workers' own preferences — how much a job must pay to attract them — and with the wages other jobs pay.
劳动供给随合格工人的数量、移民、工作的吸引力， 以及其他工作给出的工资而变化。
Here is the chain the exam likes. A tech boom raises app prices, so programmers' marginal revenue product jumps, demand shifts right, and both the wage and the jobs rise.
这是考试喜欢的一条链条： 科技繁荣抬高应用程序的价格，于是程序员的边际收益产品上升，需求右移，工资和岗位都增加。
Now the competitive case.
现在看竞争的情形。
Many firms are hiring, so no single firm can move the market wage.
雇主很多，所以没有哪一家企业能改变市场工资。
Each one is a wage taker.
每一家都是工资接受者。
That has a neat consequence: its marginal factor cost is simply the wage.
这带来一个漂亮的结论：它的边际要素成本就等于工资。
So the rule becomes one you can use in a single line — M R P equals wage: hire where marginal revenue product equals the wage.
于是这条规则可以用一句话来使用——在边际收益产品等于工资的地方雇人。
And because that rule picks a number of workers at every possible wage, the marginal revenue product curve is the firm's labour demand curve.
而且因为这条规则在任何工资水平上都能定出工人数量， 边际收益产品曲线就是企业的劳动需求曲线。
Now the calculation this unit is tested on.
现在来做这个单元必考的计算。
A firm sells its output for five dollars a unit and hires workers at a wage of thirty dollars.
企业的产品每单位卖五美元，雇工人的工资是三十美元。
Here is what each extra worker adds to output.
这是每多一个工人增加的产量。
Pause here and work it out yourself.
先暂停，自己算一算。
Multiply each marginal product by the five dollar price to get marginal revenue product: sixty, fifty, forty, thirty, twenty.
把每个边际产量乘以五美元的价格，得到边际收益产品：六十、五十、四十、三十、二十。
Now compare each one with the thirty dollar wage.
再把每一个与三十美元的工资比较。
The first four each bring in at least what they cost; the fifth brings in only twenty.
前四个工人带来的收入至少等于他们的成本； 第五个只带来二十美元。
Hire four workers — the fourth adds exactly what she costs, and at the margin that is still worth doing.
雇四个工人——第四个人带来的收入正好等于成本， 在边际上，这依然值得做。
One more rule, and it is marginal thinking again.
还有一条规则，仍然是边际思维。
To find the least-cost combination of inputs, spend so that the last dollar on each input buys the same extra output — marginal product per dollar equal across inputs.
要以最低成本生产任何产量， 就要让花在每种投入上的最后一美元，买到相同的额外产量。
Say a worker costs twenty dollars and adds forty units — that is two units per dollar.
假设一个工人成本二十美元，增加四十单位产量——也就是每美元两单位。
A machine costs ten dollars and adds thirty units — three per dollar.
一台机器成本十美元，增加三十单位——每美元三单位。
The machine is the better buy, so move money towards capital.
机器更划算，所以把钱转向资本。
Use more capital and its marginal product falls; use less labour and labour's rises, until the two ratios meet.
多用资本，资本的边际产量下降；少用劳动，劳动的边际产量上升，直到两个比值相等。
Now change one thing.
现在改变一个条件。
Suppose there is only one buyer of labour in the whole town — one mine, one hospital, one factory.
假设整个镇上只有一个劳动的买方——一座矿、一家医院、一间工厂。
That is a monopsony.
这就是买方垄断。
Because it is the whole market, it faces the upward supply curve itself.
因为它就是整个市场，它自己面对那条向上倾斜的供给曲线。
To hire one more worker it must offer a higher wage, and it must pay that higher wage to everyone already working there.
要多雇一个工人，它必须开出更高的工资，而且必须把这个更高的工资付给所有已经在岗的人。
So the true cost of one more worker is above the wage, and the marginal factor cost curve lies above the supply curve.
所以多雇一个工人的真实成本高于工资，边际要素成本曲线位于供给曲线之上。
Let's make that concrete.
我们用数字来说明。
To get one worker the mine must pay ten dollars an hour.
要雇到一个工人，矿场每小时必须付十美元。
To get a second it must pay twelve — and the first worker now gets twelve as well, because everyone doing the same job is paid the same.
要雇到第二个，必须付十二美元——而第一个工人现在也拿十二美元， 因为做同样工作的人拿同样的工资。
So the wage bill jumps from ten dollars to twenty-four.
于是工资总额从十美元跳到二十四美元。
The second worker really costs fourteen dollars, not twelve.
第二个工人真正的成本是十四美元，而不是十二美元。
At the third worker the wage is fourteen but the extra cost is eighteen.
到第三个工人，工资是十四美元，但额外成本是十八美元。
Marginal factor cost is always above the wage, and the gap keeps growing.
边际要素成本永远高于工资，而且差距越拉越大。
Now the graph the free-response question asks you to draw.
现在是自由问答题要求你画的那张图。
Labour supply slopes up.
劳动供给向上倾斜。
Marginal factor cost sits above it and rises more steeply.
边际要素成本位于它之上，而且更陡。
Marginal revenue product is the demand curve, sloping down.
边际收益产品是需求曲线，向下倾斜。
The firm hires where marginal factor cost meets marginal revenue product, and that fixes the number of workers.
企业在边际要素成本与边际收益产品相交的地方雇人，这就定下了工人数量。
Now the step that costs students the mark: read the wage down from there to the supply curve, not across to the crossing.
接下来是最容易失分的一步：从那里向下读到供给曲线上的工资，而不是横着读到交点。
Compare that with the competitive outcome. A monopsony hires fewer workers and pays a lower wage than a competitive market would: fewer jobs, lower pay, and that gap is the whole point of the diagram.
把它和竞争的结果比一比：工人更多，工资更高。
And that leads to a result that surprises people.
这带出一个让人意外的结论。
In a competitive labour market, a minimum wage set above the equilibrium wage causes unemployment: more people want to work than firms want to hire.
在竞争性劳动市场上，把最低工资定在均衡工资之上会造成失业： 想工作的人多于企业想雇的人。
But in a monopsony, a well-set minimum wage can raise the wage and the number of jobs at the same time.
但在买方垄断中， 一个设定得当的最低工资可以同时提高工资和岗位数量。
It fixes the wage, so the firm no longer has to raise pay for everyone to hire one more.
它把工资固定住，企业就不必为了多雇一个人而给所有人加薪。
Set it too high, though, and unemployment returns.
不过如果定得太高，失业还是会回来。
Four marks students give away every year.
每年学生都会白白丢掉四个分。
First, marginal revenue product is marginal product times the price of the output — show that multiplication.
第一，边际收益产品等于边际产量乘以产品价格—— 把这个乘法写出来。
Second, in a monopsony the wage comes off the supply curve, never off the marginal factor cost curve.
第二，在买方垄断中，工资要从供给曲线上读， 绝不能从边际要素成本曲线上读。
Third, a change in the product market changes marginal revenue product, because factor demand is derived.
第三，产品市场的变化会改变边际收益产品， 因为要素需求是派生需求。
And fourth, a change in fixed cost never changes how many workers to hire; hiring is a marginal decision.
第四，固定成本的变化绝不会改变雇多少工人； 雇佣是一个边际决策。