In 2006, Dr. Carol Look conducted an 8 week study wherein over 100 people followed written instructions to use EFT for a variety of emotional and vision issues.
The participants were worldwide and both the written instructions and the feedback were done via the internet. Accordingly, this qualifies as an experiment rather than a pristinely controlled scientific study.
Nonetheless, the results are eye opening (pardon the pun). Also, great care was taken to properly report the details and statistics regarding the experiment.