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Finance & economics
财经版块
Agglomeration benefits
聚集效应
Up in smoke
灰飞烟灭
Do economists overrate big cities?
经济学家是否高估了大城市？
Judged by their revealed preferences, people love cities.
从人们所表现出来的偏好判断，人们热爱城市。
Metropolises such as London and New York are bursting at the seams, with house prices to match.
像伦敦和纽约这样的大都市已经人满为患，房价也相应高涨。
China, meanwhile, can boast at least six cities bigger than either of them.
同时，中国拥有至少六个比它们都更为庞大的城市。
Across the world, 25% of people live in cities of over a million, up from just 15% six decades ago.
在全球范围内，25%的人口居住在人口超过一百万的城市中，而六十年前这一比例仅为15%。
Economists tend to think this is a great development.
经济学家倾向于认为这是巨大的发展。
Cities, they argue, benefit from “agglomeration”, the consequence of so many people living in close quarters.
他们认为，城市受益于“集聚效应”，这是众多人口密集聚居的结果。
For one thing, government and businesses can run more efficiently: scale helps everything from public transport to the recruitment of staff.
一方面，政府和企业可以更高效地运作：规模对从公共交通到员工招聘的一切事务都有助益。
For another, finding the next big idea is easier when like-minded people crowd together.
另一方面，当志同道合的人聚集在一起时，找到下一个伟大创意会更容易。
Although London makes up 15% of Britain’s population, it counts for 22% of its economic output.
伦敦虽然占英国人口的15%，但占英国经济产出的22%。
But have economists overestimated the benefits of big cities?
但是经济学家是否高估了大城市的好处呢？
That is what a new working paper by Matthew Turner and David Weil, both of Brown University, suggests.
布朗大学的马修·特纳和大卫·韦尔的一篇新工作论文提出了这个观点。
Their analysis applies existing estimates of the impact of agglomeration on economic efficiency and the pace of invention to a model of the American economy.
他们的分析把对集聚效应对经济效率和发明速度的影响的现有估计应用于美国经济模型。
This allows the researchers to answer a provocative question: how different would America look if, from 1900 to 2010, no urban area had grown to a population of more than 1m people?
这使得研究人员能够回答一个发人深省的问题：如果从1900年到2010年，没有一个城市地区的人口增长到超过100万人，那么美国会有多大的不同？
According to their calculations, the answer is “not all that much”.
根据他们的计算，答案是“并没有太多不同”。
Growth would have been slower, but only a bit: the researchers reckon that America’s total output would have been 8% lower in 2010 than it was in reality.
经济增长应该会放缓，但幅度不大：研究人员估计，2010年美国的总产出将比实际水平低8%。
Such an income gap is smaller than that between America and Denmark.
这样的收入差距比美国和丹麦之间的差距都更小。
Cities do make residents more productive, but the size of the conurbation does not matter too much.
城市确实能让居民更有生产力，但城市群的规模并不太重要。
As Mr Weil puts it: “Without big cities, we would still have modern life as we know it.”
正如韦尔所说：“没有大城市，我们仍然会拥有现在的现代生活。”
City enthusiasts may not be entirely persuaded by the authors’ number-crunching, which inevitably relies on some heroic assumptions.
城市爱好者可能不会完全被作者的数据计算所说服，这些计算不可避免地依赖于一些大胆的假设。
Edward Glaeser of Harvard University points out that Messrs Turner and Weil presume innovation becomes harder over time, as the easy wins are taken, meaning big cities gain less than they would otherwise from bringing the best and the brightest together.
哈佛大学的爱德华·格莱泽指出，特纳和韦尔认为，随着容易取得的成果被获取，创新会变得越来越难，这意味着大城市无法像原本那样从汇聚最优秀和最聪明的人才中获得那么多好处。
Whether this pattern will continue in the future is uncertain.
这种模式在未来是否会继续，尚不确定。
Artificial-intelligence boosters would certainly contend that innovation is likely to accelerate in the coming years.
人工智能的支持者肯定会争辩说，未来几年创新可能会加速。
There is plenty about city life that is unpleasant.
城市生活有很多令人不愉快的地方。
In September, for instance, Eric Adams, New York’s mayor, convened a “National Urban Rat Summit”, as part of his “war on rats”.
例如，在去年9月，纽约市长埃里克·亚当斯召开了一次“全国城市老鼠峰会”，这是他“灭鼠之战”的一部分。
But big cities also clearly afford benefits other than growth, as Mr Weil is keen to point out.
但是正如韦尔热切地指出的那样，大城市除了带来增长之外，显然还提供了其他好处。
Ultimately, high housing costs reflect people’s desire to live in them, and this does not only stem from sizzling job markes.
总而言之，高房价反映了人们对居住在大城市的渴望，这不仅仅是因为火热的就业市场。
