Fenwei has selected representative coal mines and enterprises from main coal areas in Shanxi, Shaanxi, Inner Mongolia,  as the dynamic monitoring points of production, sales and inventory. Their prices, production, inventories and profits are tracked on a regular basis to produce dynamic monitor data for the quantitative study of production, sales and inventories of Chinese coal and coke producers.

We decide the number of sample mines in each province based on their production.
Priority is given to those mines that sell coal at northern ports.
Most of the mines are large state-owned mines, supplemented by local and private mines.
Under the same ownership, large mines will be given priority, while rational distribution of calorific value is considered for mines of the same capacity.
Mines of the same capacity and ownership will be chosen to substitute those that need undergo bankruptcy regrouping. In this case, subscribers will be informed timely.