很多宏观经济现象都可以从人口(population and demographics)的角度来认识. 最典型的例子就是二战后大量婴儿的出生(baby boomers)形成了人口分布曲线上的一个鼓包(bulge)，先是带动了日用品的消费(尤其是婴儿用品, like Johnson & Johnson), 造就了战后经济的繁荣，随后几十年中这些人成为了年富力强的一代，又造就了高科技，教育，医疗，金融业和房地产业的繁荣(But now they are walking into the sunset in Florida...)

这一波金融危机看似是信贷，房地产过度膨胀的结果，但从人口和人口结构的角度来分析，more and more boomers at their peak earning age require more and increasingly sophisticated vehicles for their investments, such as real estate and exotic fixed income securities.

还有一些有趣的例子，80年代美国城市的犯罪率的大幅下降很可能是因为十几年前避孕手段的普及和堕胎的合法化使得出生在问题家庭的婴儿大量减少。

中国为什么晚于西方世界进入工业化，很大的原因就是因为人力资源的丰富.有史料记载，明清时期一吨铁的价钱可以雇佣100个(or 1000个?记不清了)壮劳力, 如果这样，谁会bother去发明蒸汽机？发明出来了也没有人愿意造，愿意用.

电话，电报都是美国人发明的(Go USA!), 而不是经济，科技大大领先于美国的欧洲. why? A British General once said, only Americans need telegraph, we have enough messenger boys!

扯远了. 回到中国的房地产市场上来。中国的经济社会也会因为人口结构的变化而变化，我们的父辈大多兄弟姐妹好几个,而我们这一代人已经有了不少独生子女。独生子女这一代已经进入了生育高峰，而且他们中间还出现了数量可观的丁克一族，one reason being, ironically, that they can not afford both a house and a kid.

虽然在短期或是小范围内会有随机波动，但微观现象在长时间和大范围内will cancel each other out. 宏观现象是由宏观因素决定的，这一点不会改变。People will eventually realize that leaving a 1 million RMB home empty or renting it out for 1000 a month, minus carry costs and depreciation, is not a good investment.

当然不排除一些有先发优势的大城市由于一定时期内资金，人才的持续流入而造成房价在较长时期内居高不下，这是由于微观因素可以在一定时期，一定范围内占主导，就像下山时有的时候有的地方也会遇到一个上坡。这时的表象就是微观（secular random variation)和宏观因素(global down trend)的叠加，而宏观因素总是持续而长久的, 人口的构成不会在短期(比如说一代人)内发生变化.

有人会说housing price will go up because of the increasing scarcity of land. Unfortunately, that’s an urban legend(on pun intended) real estate industry created and fed to you and hope that you’d believe, as many actually did. If you think about it carefully, with the population going down or flat, and agricultural techniques more and more advanced, the land will become more abundant, not scarce.


disclosure of holdings: 左总在国内有房两套.