Measuring Strong, Skillful, Good and Transpersonal Will: The development of the Multidimensional Will Scale.

Background and objective: This cross-sectional study aimed to provide a scale to assess different aspects of the will based on Roberto Assagioli's theory. Methods and results: The scale development followed three steps. Step 1 focused on operationalizing the construct and developing the items. It was carried out through several phases of item generation and refinement, resulting in a pool of 38 items. At Step 2 we tested the psychometric properties of the initial 38-item scale with the goal of excluding the items that weakened the structural validity and reliability of the scale. Descriptive, internal consistency, and exploratory factor analyses statistics were computed on a large sample (Sample 1: N = 587; age: M = 21.55, SD = 4.14, 66% female) and they led to a five-dimension model (Strong, Skillful, Good toward Self and Other, and Transpersonal Will) and the exclusion of 15 items. Analyses conducted at Step 3 on a different sample (Sample 2: N = 683; age: M = 34.09, SD = 16.27, 54% female) allowed for further refinement of the scale. Confirmatory factor analysis conducted on the resulting 19-item scale showed a good fit for the five-factor model (χ2 (142) = 507.63, p<.001, TLI =.91; CFI =.93; RMSEA =.06 [90%CI:.06‒.07]), and evidence of its invariance across genders and ages was provided. Reliability indices (internal consistency and intraclass correlation coefficients) were adequate (ranging from.66 to.83) and correlations with measures of related constructs supported the external validity of the scale. Conclusion: This study provides researchers, therapists, and counselors with an efficient measurement tool to assess Assagioli's construct of will. [ABSTRACT FROM AUTHOR]