Outcome studies of child psychotherapy have sometimes been
categorized into two broad types of studies.
Ideally, psychotherapy outcome investigators first conduct
“efficacy studies”, where internal validity is at the
forefront and where considerable control is exercised
over and within the experimental design (Hoagwood,
Hibbs, Brent, & Jensen, 1995). In efficacy studies, often:
(a) specific inclusion and exclusion criteria will be defined
in order to restrict the sample to children exhibiting only
the specific behavioral/emotional problem area upon
which the treatment focuses; (b) the sample will be
randomly assigned to treatment and comparison groups;
(c) in order to allow for assignment to a no-treatment
control group, the sample will not be seeking treatment
(i.e. not clinic-referred); and (d) the investigators will
exercise a high degree of control over the intervention
(e.g. spend several months training therapists who are
hired specifically for the project, see, e.g., Lewinsohn,
Clarke, Hops, & Andrews, 1990).
“Effectiveness studies” are conducted where the focus
is more on external validity and generalizability. In
contrast to efficacy studies, effectiveness studies generally:
(a) take place in naturalistic settings, where the
mental health treatment of children actually occurs (e.g.
in clinics); (b) use heterogeneous samples that are actually
seeking services; (c) involve practitioners rather than
research therapists; and (d) allow therapists more control
over the intervention (see, e.g., Weisz & Weiss, 1989).