title: Enhancing the validity and utility of randomized clinical trials in addictions treatment research: II. Participant samples and assessment.
abstract: OBJECTIVE
  This paper is the second in a series that describes strategies for optimizing the validity and utility of randomized clinical trials (RCTs) in addictions treatment research. Whereas the first paper focused on treatment implementation and research design, here we address issues pertaining to participant samples and assessment methods.
  
  
  METHODS
  With respect to participant samples, sections focus on the definition of study populations; informed consent; sample size and statistical power; recruitment and enrollment; sample retention; and participant tracking systems. Assessment topics include eligibility screening and baseline assessment; treatment-related variables; outcome measures; the frequency of follow-up evaluation; and assessment process. A final section highlights the importance of pilot testing.
  
  
  CONCLUSIONS
  Sample recruitment and retention strategies are needed that safeguard both internal and external validity. Daily estimation assessment procedures are recommended because of their versatility for creating a range of outcome measures. Assessment batteries should include measures that permit the investigation of treatment processes and mechanisms of action.
authors.affiliation: University of South Florida, FL 33620-8200, USA. fdelboca@cas.usf.edu
authors.forename: Frances K
authors.initials: FK
authors.lastname: Del Boca
authors.forename: Jack
authors.initials: J
authors.lastname: Darkes
mesh_terms: D032984:Ethics, Research; D006801:Humans; D017063:Outcome Assessment, Health Care / Q000592:standards*; D018579:Patient Selection / Q000941:ethics*; D010865:Pilot Projects; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D015203:Reproducibility of Results; D012107:Research Design / Q000592:standards*; D019966:Substance-Related Disorders / Q000517:prevention & control*