Participant assessments: Baseline assessments using the
Global Appraisal of Individual Needs (GAIN), [54] which is a
widely used comprehensive biopsychosocial assessment that
integrates research and clinical assessment into one structured
interview, were conducted by trained staff with adolescents
at intake to outpatient or residential treatment. The GAIN’s
main scales have been shown to demonstrate good internal
consistency (with alphas greater than .90 on main scales, .70 on
subscales) and test–retest reliability (Rhos greater than .70 on
days/problem counts, kapp as greater than .60 on categorical
measures) and to be highly correlated with measures of use based
on timeline follow-back methods, urine tests, collateral reports,
treatment records, and blind psychiatric diagnosis (Rho of .70 or
more, kappa of .60 or more) [6,54-63]. Copies of the instruments,
manual, publications, and documentation on the 100 plus scales
in the GAIN are available at www.chestnut.org/li/gain. In addition
to the baseline assessment, a follow-up version of the GAIN was
completed at 3 and 6 months post-intake. Participants were
compensated $30 in gift cards for the time and effort required
to complete follow-up measurement interviews, as well as an
additional $10 in gift cards for completing interviews within 1
week of its due date.