When we talk about the health of an economy, we focus on macroeconomics, which deals with the performance, structure, behavior and decision-making process that deal with the growth, inflation and employment (or unemployment). We also take into consideration microeconomics that studies the behaviors of individuals and enterprises in deciding the allocation of resources, as well as the effects of a country's economic policies. Amid all this economics jargon (for lay individuals), the role of the informal economy gets lost.

Unwittingly, the latest population data of Beijing, Shanghai and Guangzhou, China's three major metropolises, shed some light on the informal economy (or sector) and people engaged in it. The population data of the three cities for the first half of the year show the number of residents in central Beijing declined and the growth rate in Guangzhou slowed. Then comes the disturbing part of the data: those moving out of the metropolises are mainly poorer residents, or those working in the informal sector.

The moving out of poorer residents, or "low-end population" as some media outlets have humiliatingly described them, is no big news, right? Wrong.