Larry Summers on the problem with Fannie Mae and Freddie Mac:

What went wrong? The illusion that the companies were doing virtuous work made it impossible to build a political case for serious regulation. When there were social failures the companies always blamed their need to perform for the shareholders. When there were business failures it was always the result of their social obligations.

This is precisely the same type of danger that social entrepreneurs face.

Harper's on alternative energy as the bubble which will take over from the housing bubble that is deflating. This is really believable to me, seeing as to how much press and attention has been spent on alternative energy despite the complete absence of any fundamental efficiency milestone. Both the Masdar effort in Abu Dhabi and McKinsey's carbon supply curve (which doesn't really emphasize alternative energy, but lives in the same space) come to mind.

Excerpt:

We have learned that the industry in any given bubble must support hundreds or thousands of separate firms financed by not billions but trillions of dollars in new securities that Wall Street will create and sell. Like housing in the late 1990s, this sector of the economy must already be formed and growing even as the previous bubble deflates. For those investing in that sector, legislation guaranteeing favorable tax treatment, along with other protections and advantages for investors, should already be in place or under review. Finally, the industry must be popular, its name on the lips of government policymakers and journalists. It should be familiar to those who watch television news or read newspapers.

There are a number of plausible candidates for the next bubble, but only a few meet all the criteria. Health care must expand to meet the needs of the aging baby boomers, but there is as yet no enabling government legislation to make way for a health-care bubble; the same holds true of the pharmaceutical industry, which could hyperinflate only if the Food and Drug Administration was gutted of its power. A second technology boom—under the rubric “Web 2.0”—is based on improvements to existing technology rather than any new discovery. The capital-intensive biotechnology industry will not inflate, as it requires too much specialized intelligence.

There is one industry that fits the bill: alternative energy, the development of more energy-efficient products, along with viable alternatives to oil, including wind, solar, and geothermal power, along with the use of nuclear energy to produce sustainable oil substitutes, such as liquefied hydrogen from water.

The article goes on to list evidence from the press and ongoing legislation.

Assume that you live in a culture that, for some reason or another, values having a male heir in the family. Families adopt the strategy of having children until the first male child is born. If the natural sex ratio is 1:1, what is the expected sex ratio in this culture?

It remains at 1:1. Here's why. Each family has 1 boy. As for females, there is a 50% chance of having no girls, 25% chance of having 1 girl, 12.5% chance of having 2 girls, and so forth. So the average number of girls is (n-1)/2^n summed from n = 1 to infinity.

Therefore just following the strategy above does not change the sex ratio. In fact, it is possible to prove that no stopping strategy would change the sex ratio. Here's how:

After having m children, a couple has to decide whether to have the (m+1)st child, based on those m children. Since the (m+1)st child's sex is completely independent of the already born m children, it does not on the average change the existing number of boys - girls. This means that the average with or without the stopping will remain the same, namely at 1:1.

How is one to get a skewed sex ratio then? Wikipedia (HT: Leeping):

However, other Asian regions also have higher than average ratios, including Taiwan (110:100), and South Korea (108:100), which do not have a family planning policy.^[70] Many studies have explored the reason for the gender-based birthrate disparity in China as well as other countries. A study in 1990 attributed the high preponderance of reported male births in mainland China to four main causes: diseases which affect females more severely than males; the result of widespread under-reporting of female births;^[71] the illegal practice of sex-selective abortion made possible by the widespread availability of ultrasound; and finally, acts of child abandonment and infanticide.

This is actually a special case from the very powerful and counter-intuitive Optional Stopping Theorem.