Brief Description

The Session Impact Scale (SIS) is a self-report tool completed by the client at the end of each therapy session. It includes 16 statements concerning the client’s experiences during the session, each accompanied by a brief explanation. These statements assess the impact of the session on multiple levels, such as perceived helpfulness, the therapeutic relationship, understanding, problem-solving, and possible negative experiences. The scale has been translated and adapted into Greek, maintaining its original meaning and ensuring clarity for Greek-speaking populations.

Purpose

The SIS aims to evaluate the impact of a therapy session as experienced by the client. It serves as a tool to monitor therapeutic progress and provide feedback to the therapist.

Scoring Method

The scale consists of three main subscales. The first is Task Impact (items 1–5), the second is Relationship-Bond Impact (items 6–10), and the third is Negative or Conflicting Impact (items 11–16). Each item is rated on a five-point scale from 1 (not at all) to 5 (very much), with clients indicating how much each statement represents their experience during the session.

Validity

The Greek version of the SIS retains the conceptual validity of the original tool, supported by thorough translation and psychometric procedures. Factor analysis confirmed alignment with the dimensions found in the original English version.

Reliability

Internal consistency of the SIS has been repeatedly verified using Cronbach’s alpha. In the original version, Task Impact showed reliability of 0.84, Relationship-Bond Impact 0.91, and Conflicting Impact 0.70. In the Greek version, reliability ranges from 0.67 to 0.85 across the subscales of understanding, problem-solving, relationship, and negative impact.

Data Analysis and Use

The SIS is a valuable tool for both research and clinical practice, enabling documentation of the client’s subjective experience after each session. Collected data can help identify patterns in therapeutic progress, strengthen therapist-client collaboration, and evaluate the effectiveness of different therapeutic approaches.

References

Elliott, R., & Wexler, M. (1994). Measuring the Impact of Sessions in Process–Experiential Therapy to Depression: The Session Impacts Scale. Journal of Counseling Psychology, 41(2), 166–174.
Reynolds, S., Stiles, W. B., Barkham, M., Shapiro, D. A., et al. (1996). Acceleration of changes in session impact during contrasting time-limited psychotherapies. Journal of Consulting and Clinical Psychology, 64(3), 577–586.
Stiles, W. B. (1980). Measurement of the impact of psychotherapy sessions. Journal of Consulting and Clinical Psychology, 48, 176–185.
Stiles, W. B., & Snow, J. S. (1984). Counseling session impact as viewed by novice counselors and their clients. Journal of Counseling Psychology, 31, 3–12.