It is a good idea to read the citation, at least in part. I am quoting from conclusion as that's the only part I am interested and read.

Today, I would argue that given the limitations of the existing literature we still have essentially no credible empirical evidence on the seemingly simple question of whether stronger patent rights – either longer patent terms or broader patent rights – encourage research investments into developing new technologies. While researchers have recently begun to make progress on the more limited question of how patents on existing technologies affect follow-on innovation (Galasso and Schankerman, 2015; Sampat and Williams, 2015), evidence on the overall effects of patents on research investments are needed as one input into optimal patent policy design.