The researchers used a method called set pair analysis to study the water quality of the Daling River in Fuxin. They looked at data from 2003 and found that the water quality was generally at level V, the lowest level. However, they also discovered that some areas, like Gahaixi and Dongliang Bridge, were more polluted than others, like Moon Bay. This method was shown to be accurate and reliable for assessing river water quality, and could be useful in other areas too.