. Author manuscript; available in PMC: 2013 May 11.

Published in final edited form as: J Subst Abuse Treat. 2002 Sep;23(2):73–80. doi: 10.1016/s0740-5472(02)00255-6

Table 1.

Design elements supporting internal and external validity used in MET and MI protocols

Elements supporting internal validity	Elements supporting external validity
Random assignment to treatments	Comparison condition = treatment as usual
Manual guided treatments	Few restrictions on patient participation
Objective outcome measures, including urinalyses	Clinicians are volunteers from community programs
Training and ongoing supervision of therapists	Study conducted at 11 community treatment programs
Monitoring of treatment delivery, fidelity via independent evaluation of session tapes	Brief assessment battery (approximately 45 minutes for MI, 90 minutes for MET)