Descriptive statistics and correlation coefficients are listed in
Table 2. Estimates of direct effects from mediation models using
patient-rated therapeutic alliance are displayed in Table 3. Direct
effects from serial mediation analyses showed that early CALPAS
ratings were positively predicted by pretreatment Agreeableness,
but not by Neuroticism, Extraversion, Openness, or Conscientiousness.
In all models, early CALPAS ratings positively predicted
late CALPAS ratings. Moreover, in all models, late CALPAS
negatively predicted treatment outcome. Neuroticism was the only
pretreatment personality trait that showed a direct effect on
treatment outcome, such that higher Neuroticism predicted
poorer treatment outcomes, as measured by posttreatment BDI-II
scores (p¼.044); however, this effect was not replicated in models
predicting posttreatment Ham-D scores. Estimates of indirect effects
from all mediation models are displayed in Table 4. The indirect
effect of Agreeableness on treatment outcome via early and
late alliance was significant. No other significant serial mediation
effects were observed for the remaining five-factor model domains.
We did observe additional evidence for the indirect effects
of Extraversion, Openness, and Agreeableness; however, these
results varied depending on the time at which CALPAS ratings
were obtained and our measure of depressive symptoms. For example,
Openness showed significant indirect effects on posttreatment
depression scores via late ratings of alliance. Extraversion
similarly showed significant indirect effects on posttreatment depression
scores via late ratings of alliance; however, this was only