A time-lagged, actor–partner interdependence analysis of alliance to the group as a whole and group member outcome in overweight and obesity treatment groups.

A time-lagged design was used to examine how the perceptions of alliance to the group as a whole by the other group members at an earlier point in the group were related to an individual group member’s perceptions of alliance to the group as a whole at a later point in the group. We also examined how treatment outcome moderated this relationship. Seventy-three patients diagnosed as overweight or obese participating in 10 short-term therapy groups provided data for analyses. Group members completed measures of cohesion to the group and alliance to the group as a whole at the third, sixth, and last session of 12-session groups as well as pre- and posttest ratings on Obesity-Related Well-Being and the Outcome Questionnaire– 45. As hypothesized, earlier ratings of alliance to the group as a whole by the other group members were related to later ratings of alliance to the group as a whole by the group member. Also as hypothesized, when group members had a better outcome, there was a significant positive relationship between perceptions of alliance to the group as a whole by the other group members at an earlier point in the group and an individual group member’s perceptions of alliance to the group as a whole at a later point in time. When members had a worse outcome, there was no relationship between perceptions of alliance to the group as a whole by the other group members at an earlier point in the group and an individual group member’s perceptions of alliance to the group as a whole at a later point in the group.