Rather than relying on complex/tedious data collection, sometimes an easy indicator is right there on your plate.
According to the South China Morning Post, the country’s National Development and Reform Commission has found that sales of zha cai, a pickled mustard tuber, provide a better guide to population flows than often unreliable provincial statistical data. As an unnamed planner explained to the Economic Observer:
“Under normal circumstances, urban consumption levels of convenience foods such as instant noodles and pickled mustard is essentially constant. Therefore, we can assume that volume changes are mainly caused by a city’s floating population.”