Rasch Analysis of the Norwegian Self-Efficacy for Therapeutic Use of Self Questionnaire

PURPOSE: Occupational therapists need self-efficacy in therapeutic encounters. Inspired by the Intentional Relationship Model (IRM; Taylor, 2008), measurement tools have been developed and recent research has investigated their psychometric properties by classical test-theory approaches (e.g., Bonsaksen & Carstensen, 2018). However, modern approaches such as Rasch analysis allows separating the properties of items and responders, so the rating scale functioning of the assessment can be evaluated. The purpose of the current study is to examine the psychometric properties of the Norwegian version of the three-part questionnaire ‘Self-Efficacy for Therapeutic Use of Self’, using the Rasch measurement model. The specific research questions are: How does the rating scale used in the three parts of the questionnaire function? Do the items included in each of the three parts demonstrate unidimensionality? Do the participants show appropriate person response validity in each of the three measures? Do the items in each of the three measures reliably separate participants into different levels of self-efficacy? Likewise, do participants reliably separate the items and confirm the hierarchy levels?

DESIGN: The study had a survey design with four measurement times. 111 occupational therapy students (mean age 24.5 years, 79 % women, response rate 78 %) were recruited for participation by means of convenience.

METHOD: Inspired by the IRM, the three-part ‘Self-Efficacy for Therapeutic Use of Self’ questionnaire was developed. Part I is the Self-Efficacy for Therapeutic Mode Use (SETMU), Part II is the Self-Efficacy for Recognizing Interpersonal Characteristics (SERIC), and Part III is the Self-Efficacy for Managing Interpersonal Events (SEMIE). For all items in each part, respondents were asked to use the 10-point rating scale, 1 representing the lowest level and 10 representing the highest level of self-efficacy. The questionnaire was developed in English, and subsequently translated into Norwegian using forward and backward translation procedures. Due to the nature of repeated measures, a random sample dataset was created to estimate the anchor values of the item difficulties from the subjects without intra-person dependencies. Unidimensionality, rating scale structure, person response validity, item/person separation and the Wright map were evaluated by Rasch analysis for each part of the questionnaire (Wright & Linacre, 1994).

RESULTS: Unidimensionality was generally confirmed, as all items except two (Preference for touch and Intimate self-disclosures) fit the Rasch model's expectation with acceptable values of the Infit MnSq and Zstd. The 10-point rating scale did not fully maximize the measurement potentials, as there were too many rating categories. The person response validity in all three parts exceeded the pre-determined criteria (i.e. 5%) with 8.8%, 9.5% and 7% for Parts I-III, respectively; indicating problems with person validity. We found excellent item and person separation in all three parts, whereas the calibration of the person ability was generally higher than the item difficulty calibration, indicating that the items were considered relatively easy.

CONCLUSION: The ‘Self-Efficacy for Therapeutic Use of Self’ is promising to be used as a reliable and valid tool. This questionnaire could be used to tailor occupational therapy educational programs to meet students’ needs of developing self-efficacy for therapeutic use of self. The findings from the study may serve as a guide and reference for occupational therapy educators to measure students’ self-efficacy in therapeutic use of self as well as enhancing future teaching.

References

Bonsaksen, T., & Carstensen, T. (2018). Psychometric properties of the Norwegian self-efficacy for therapeutic mode use (N-SETMU). Scandinavian Journal of Occupational Therapy, 25(6), 475-480. https://doi.org/10.1080/11038128.2017.1316421

Taylor, R. R. (2008). The Intentional Relationship. Occupational Therapy and the Use of Self. Philadelphia: FA Davis.

Wright, B. D., & Linacre, J. M. (1994). Reasonable mean-square fit values. Rasch measurement transactions, 8(3), 370.