Miranda Kaye has published an article; Stellingwerff T, Kaye MP (2013) Deterrents of Modern Anti-Doping Approaches – Are the Efforts Making a Difference? J Sports Med Doping Stud 3: e131. doi:10.4172/2161-0673.1000e131, in the Journal of Sports Medicine and Doping Studies. To summarize, indirect evidence provides support that gains in the fight against doping in sport have been made. To preserve sport as a contest of human excellence and to address the morality of doping, deterrence methods are important.
https://www.ithaca.edu/intercom/article.php/20130225093938711