The researchers used different statistical methods to figure out where pollution in the Liao River in China is coming from. They looked at water quality data from 2009 to 2011 and found that different months and areas had different pollution sources. They identified factors like oxygen-consuming organics, oil, nutrients, and fecal matter as the main pollutants in different parts of the river. This information can help manage water resources and protect aquatic life in the area.