The study looked at how well money spent on controlling pollution in Xinjiang helped the economy grow from 2001 to 2013. The results showed that the efficiency of this investment was low, meaning the money didn't do as much as it could have to clean up the environment. The problem was that the way the money was used wasn't very effective before 2010, and after 2010, the efficiency started to drop. This suggests that the way pollution control money was spent in Xinjiang wasn't very smart, and things got worse after 2010. The study suggests some ways to improve how this money is used to make things better.