Qualitative and Quantitative Validation of Tools with Rating Scales Aimed at Assessing the Quality of University Service-Learning

Service-Learning (SL) has become a highly effective learning methodology in recent years, bridging the gap between theory and practice while contextualizing learning in real-world scenarios. It has been successfully implemented across all levels of higher education, resulting in notable improvements in university students' skills. However, as a transformative methodology, SL is still in the early stages of development in terms of assessment methods. Consequently, there is a pressing need to design and validate reliable and, above all, valid measurement instruments, as the application of SL to real-world contexts is its primary value. This paper demonstrates how to optimally design and validate university SL instruments to evaluate the quality of the SL experiences at the university level from the point of view of university professors, guided by the principle of parsimony. The online modified Delphi method, Robust Unweighted Least Squares Exploratory Factor Analysis, and Confirmatory Factor Analysis have been applied to create a new instrument, the QaSLu-27, validated through a sample of 16 experts using the online modified Delphi method and 118 university teachers who implement SL projects. The results show optimal psychometric conditions for the new instrument (W = 0.11; α = 0.92; CMIN/DF=1.027; CFI= 0.979; WRMR= 0.0985; RMSEA= 0.046), leading to the development of new rating scales that allow comparisons of future users of this methodology, considering their attributional and demographic characteristics. The design of new validated instruments, capable of being used in the real world and allowing the creation of scales, will be very useful to measure the implementation of new experiences in SL, to evaluate their progress, their participants, their managers and their monitors, contributing to the establishment of this field of study in the current academic framework and in the generation of new scientific knowledge.