Economics can be fun, rewarding, and surprising. Steven Levitt has strived to tell us this in the book “Freakonomics,” coauthored with Stephen J. Dubner from New York Time. The book is indeed fascinating, full of interesting anecdotes and detective stories. How can you catch cheating among teachers? Where have all the criminals gone? What makes a perfect parent? Steven has answered all these questions in a vivid, scientific, and empirical way.

The structure of the book is unconventional. Topics and ideas are jumping all around. Stories are not internally correlated. Furthermore, some chapters (e.g., the last chapter on naming kids) are too loose and some tables are redundant. Consequently, the authors claimed that the book had no theme. Actually, it does promote one central dogma throughout the text. That is, theories and conventional wisdom should be subjected to empirical test. Let data speak themselves. We social scientists all know it. Now you morons should know it too.

In addition to illustrate the way of scientific thinking in social science, this book provokes one to think more and deeply about many social problems. In fact, there is more intriguing stuff we can say than what Steven has described in his book. Although I don’t want to spoil the readers, a couple examples will be suffice to nail down my points.

The crime rates dropped significantly in the US during the earlier 1990s.It is encouraging by itself but you may wonder why. People have proposed that economic development, more prisons and police officers, and innovative law enforcement have contributed to the decrease of crime rates. In 1999, Steven proved his smartness by suggesting that the legalization of abortion 18 years ago caused the decrease. Because those unwanted children are likely to be criminals, physically eliminating them through abortion makes fewer criminals. Indeed, those states that legalized abortion earlier than other states showed an earlier decrease of crime rates. The reasoning between abortion and crime rates is the most compelling story in the whole book.

Then how could other people miss this? Because abortion is politically sensitive, not many people are willing to talk about it. After Steven published his paper, he received assaults from all sorts of people. People called him “downright evil” and “racist.” Sadly, truth is often buried in the blind area.

Are there more questions besides Steven’s illustration? Yes, there are more. You want to know how abortion affects the crime rates. It is even more important to know how those survived potential “criminals” did not become criminals. Is it possible that fewer criminals around can reduce the chance of those potentials becoming criminals? What is the mechanism of reducing crime rates by education, economic development, and police enforcement? After all, abortion is only a partial and probably unwanted solution to reduce crime rates.

The story of disappearing criminals testifies that creative thinking is a powerful tool. On the other hand, stories told in the chapter about perfect parents showed that ill designed analysis in empirical studies could yield misleading answers.

For example, many people believe that a good school can improve students’ academic performance. Most students from good schools can attend better college than those from bad schools. Students in Harvard, Yale, and other Ivy League Universities are exclusively from good schools. Unintentionally, Chicago Public School did a social experiment on this issue. Those who wanted to change schools were subject to a citywide lottery. After several years, those who remained in the original schools had similar academic performance to those who changed schools. They had the same graduation rates.

The results are puzzling. Nevertheless, Steven made a strong conclusion that our convention wisdom on this issue was wrong. Is his conclusion true? Not really. A second thought will lead us to question the study’s outcomes. It seems that the outcomes-state standard exams and graduation rates are too weak. It is true that those who wanted to change schools were motivated students. They were already good students. Therefore, state exams and graduations were not big problems for them. To determine the difference, one should examine more powerful outcomes such as SAT score, college, and college performance. Ironically, when comparing the academic performance between black and white students, Steven still used the fact that students in good schools performed better than those in bad schools did.

Another example is whether reading to kids will improve kids’ future academic performance. Analyses from the Earlier Childhood Longitudinal Study suggested that reading to kids would not significantly help them. Instead, factors such as family with high socioeconomic status and the number of children books at home were strongly related to the later achievement. This conclusion is nonsense. I am not sure how the author did the analysis. Given the strong correlations among these factors, if they put all these variables in the same model and used some statistical techniques to select significant ones (such as stepwise regression), it is not surprising that some of them were insignificant. In fact, if a family has many books at home, it is hard to imagine that parents will not read to their kids. More books only suggest more reading at home.

Steven gave us some explanations about why the quantity of books but not the reading activities mattered. He suggested, correctly, that parents’ education and other socioeconomic status determined the kid’s future performance. The number of books was an indicator, not a causal factor. The real story is, however, that reading books is indeed helpful. But its effects have been masked by parent’s education and socioeconomic status. In families with high socioeconomic status, reading books may indeed not matter much. But in low socioeconomic families, those kids whose parents read books to them will be better prepared for school than those whose parents don’t read. There may be an interaction between parent socioeconomic status and reading books.

Furthermore, it is also well known that peer influence on child growth is as important as parental influence, if not more important. If a kid was born in an education sensitive family but play with bad friends, he/she is unlikely to succeed in academics. Unfortunately, kids from similar socioeconomic background tend to play together.

Throughout the book, Steven made many strong conclusions and “rogue” reasoning. Some are more rigorous than others. It seems to me that Steven had somewhat fallen in love with his theories. Convention wisdom tells us, correctly this time, that love blinds people’s eyes. Steven failed to explore alternatives in explaining some social phenomena. A few explanations are also premature. Furthermore, Steven omitted the future research in these topics, which I think is equally important to the explanations of the problems. Neither did he describe the limitations of social research. Ignoring them may confuse less informed lay persons, while scientifically trained people may find them unsettled.

It is also interesting that the book was written in a way like a personal saga. Some stories are more detached but some sounds like a show-off. There are some rooms for the improvement in writing style.

So what are the messages from the book? I think Steven made a significant contribution in enlightening common people that religious ardor and conventional wisdom is not necessary correct. Creative and critical thinking, together with empirical test, is the key to understand the world.