The phrase "conclusive link" refers to a strong and undeniable connection between two things or ideas. It means there is solid evidence or proof pointing to a definite relationship or cause-and-effect. Full definition
But, Harris said, there is no conclusive link between insecticide or pesticide use and the widespread deaths of honey bee colonies that have been occurring in the U.S., Canada and parts of Europe. (sciencedaily.com)
The study, led by environmental chemist Robert Jackson of Duke University, was the first to find a conclusive link between fracking and groundwater pollution. (discovermagazine.com)
Nevertheless, no conclusive links have been found. (melgen.org)