Development and Initial Psychometric Evaluation of the Self-Efficacy Scale for Voice Modification in Trans Women

To develop a self-efficacy questionnaire for voice modification related to gender affirmation and to examine the internal consistency and test-retest reliability of the questionnaire among a cohort of trans women. This study was undertaken in two phases. In phase I, four Speech- Language Pathologists (SLPs) and four trans women informed the development of the Self-Efficacy Scale for Voice Modification in Trans Women (SES-VMTW). In phase II, using classical test theory, data from 31 Australian and 27 Swedish trans women who completed the SES-VMTW twice with an interim period of 3-6 weeks were analyzed for internal consistency and test-retest reliability. During this second phase, the 19 items of the SES-VMTW were subcategorized by consensus among the authors into like groups. Phase I resulted in the 19-item SES-VMTW and four subcategories were identified: 1) Change (items related to changing voice); 2) Perception (items related to the ability to perceive changes in voice; 3) Psychological (items related to engaging in voice practice despite psychological barriers; 4) Logistical (items related to engaging in voice practice despite logistical barriers). In Phase II, initial psychometric analysis was applied to the full questionnaire as well as to the subcategories. The Cronbach's alpha for the full questionnaire (α = 0.86) at both the test and retest timepoints indicates a high level of internal consistency. Item-total correlation analysis indicated that individual items correlated with the questionnaire total score, but that they generally correlated more strongly with the total score for the relevant subcategory. The Cronbach's alpha for the four subcategories of the SES-VMTW were variable but all coefficients exceeded 0.6, thus supporting the reliability of the new scale. Good test-retest reliability was demonstrated for the full questionnaire (intraclass correlation coefficient = 0.84; 95% confidence interval, 0.73-0.90, P < 0.001) and was moderate to good for the four subcategories. The findings of the current study are promising, suggesting that both the full SES-VMTW and the four subcategories can provide consistent and reliable insight into self-efficacy for trans women aiming to modify their voice as part of their gender affirmation.