Ceiling effects indicate a possible threshold structure for working alliance

This review investigated whether ceiling effects on client-reported working alliance measures represent measurement artifacts or valid information related to the formation of the working alliance. Using data from two previously published meta-analyses, a total of 92 estimates of ceiling effects were calculated based on 37 studies with 6,439 participants. Analyses examined the size of ceiling effects, relation with demographic variables, type of alliance measure, and ceiling effect stability across sessions. Moderate to large ceiling effects appeared across score distributions of multiple measures of client-rated alliance, across time administered, and across different sample characteristics such as gender, age, and ethnicity. When examined with the Session Rating Scale (SRS), analyses indicated ceiling effects had a moderate correlation with session number. When SRS ceiling effects were examined in a single study with a large sample of complete cases (N = 2,990) across seven sessions, large initial ceiling effects continued to increase slightly in size across sessions. Higher ceiling effects were also observed with the Working Alliance Inventory. Given the prevalence and relative stability of ceiling effects on score distributions, working alliance scores do not exhibit the characteristics of a normally distributed continuous variable. While the working alliance has typically been defined in terms of theoretical content such as tasks, goals, and bond, study findings suggest another key element may be a threshold structure where clients shift to an experience of the therapeutic relationship as established. Discussion focuses on directions for alliance research and clinical practice as well as study limitations. (PsycInfo Database Record (c) 2021 APA, all rights reserved).