“…For studying the effect of PBL, mixed methods analyses present a promising and rigorous evaluation framework that has already been encouraged within transportation engineering education research. Young et al( 2015) Cambell et al (1959) were among the first to discuss how finding convergence (also called triangulation) among multiple methods within the same framework can increase a study's validity. These studies can be weakened by failing to give a rationale for using mixed methods (Kajfez et al 2014.)…”