One of the finest economists in the US, Steven Levitt, tries to discover why the crime rate in the US declining in the 1990s. His answer is four factors: 3 are conventional, but one is controversial. The controversial one is the legalization of abortion. Special to abortion case, this is not the US alone. Romania also faces the same reality. The legalization of abortion in Romania contributes to crime rates several decades later.

What makes these research great? Because it evaluates many theories, assumptions and data carefully to verify what hypothesis supported by evidences and what is not.

In another realm, the fight against crime also happens at the micro-level. Police patrol in the “hotspot” area proved reducing crime in one city.

What makes these research great? Because it is very actionable. It is also a simple and practical solution. This useful policy can be replicated in many cities around the globe, and finally make the world a better place.