. Author manuscript; available in PMC: 2018 May 7.
Published in final edited form as: Contemp Clin Trials. 2018 Mar 3;68:52–60. doi: 10.1016/j.cct.2018.02.014
This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).