Session number and duration
Neither number of sessions nor session duration had an effect on child behavior in this current meta-analysis. For session
number, however, existing literature showed mixed results. Consistent with the resutls of this meta-analysis, Serketich and
Dumas (1996) also found that session number had no effect on child behavior. In contrast, Maughan et al. (2005) found that
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programs that have between two to five sessions were most efficacious. In terms of duration of sessions or intensity of
treatment, Tellegen and Sanders (2013) report that more intensive treatments intended to have larger effect sizes for
children exhibiting more severe behaviors. As all of the PMTs included in this study were intended for children with serious
difficulties, there is the possibility that heterogeneitity between studies may not be different enough to determine the effect
of session number and duration.