Samenvatting

Background: The aim of this study is to validate a newly developed nurses' self-efficacy sources inventory. We test the
validity of a five-dimensional model of sources of self-efficacy, which we contrast with the traditional four-dimensional
model based on Bandura's theoretical concepts.
Methods: Confirmatory factor analysis was used in the development of the newly developed self-efficacy measure. Model
fit was evaluated based upon commonly recommended goodness-of-fit indices, including the χ2 of the model fit, the Root
Mean Square Error of approximation (RMSEA), the Tucker-Lewis Index (TLI), the Standardized Root Mean Square
Residual (SRMR), and the Bayesian Information Criterion (BIC).
Results: All 22 items of the newly developed five-factor sources of self-efficacy have high factor loadings (range .40-.80).
Structural equation modeling showed that a five-factor model is favoured over the four-factor model.
Conclusions and implications: Results of this study show that differentiation of the vicarious experience source into a
peer- and expert based source reflects better how nursing students develop self-efficacy beliefs. This has implications for
clinical learning environments: a better and differentiated use of self-efficacy sources can stimulate the professional
development of nursing students.