Nursing Profession Self-Efficacy Scale—Version 2: A Stepwise Validation with Three Cross-Sectional Data Collections

Background: The nursing professional self-efficacy scale (NPSES) is one of the most used self-reporting tools for assessing nursing self-efficacy. Its psychometric structure was described differently in several national contexts. This study aimed to develop and validate version 2 of the NPSES (NPSES2), which is a brief version of the original scale selecting items that contribute to stably detecting attributes of care delivery and professionalism as descriptors of salient aspects of the nursing profession. Methods: Three different and subsequent cross-sectional data collections were employed to reduce the number of items to generate the NPSES2 and validate its new emerging dimensionality. The first (June 2019–January 2020) involved 550 nurses and was used to reduce the number of the original scale items by using a Mokken scale analysis (MSA) to ensure the selection of items consistently with the invariant item ordering properties. The subsequent data collection was performed to conduct an exploratory factor analysis (EFA) involving 309 nurses (September 2020–January 2021), and the last data collection (n = 249) was performed to cross-validate with a confirmatory factor analysis (CFA), the most plausible dimensionality derived from the EFA (June 2021–February 2022). Results: The MSA led to the removal of twelve items and retention of seven items (Hs = 0.407, standard error = 0.023), which showed adequate reliability (rho reliability = 0.817). The EFA showed a two-factor solution as the most plausible structure (factors loading ranged from 0.673 to 0.903; explained variance = 38.2%), which was cross-validated by the CFA that showed adequate fit indices: χ(2) (13, N = 249) = 44.521, p < 0.001; CFI = 0.946; TLI = 0.912; RMSEA = 0.069 (90% CI = 0.048–0.084); SRMR = 0.041. The factors were labeled as care delivery (four items) and professionalism (three items). Conclusions: NPSES2 is recommended to allow researchers and educators to assess nursing self-efficacy and inform interventions and policies.