One personality factor, neuroticism, predicted poorer outcome in both types of group. Three factors predicted good outcomes with both treatments: extraversion, conscientiousness, and openness.
Yalom presents empirical evidence that neuroticism, measured via the NEO-FFI, functions as a systematic predictor of therapeutic failure across both interpretive and supportive group modalities.
, The Theory and Practice of Group Psychotherapy, Fifth Edition, 2008thesis