Self and peer assessments have been identified as effective strategies to develop a deeper understanding of complex concepts, enhance meta-cognitive capacity, and support learner self-efficacy. This study examines data related to peer and self-assessment exercises completed within a university engineering programme (n=61). Data related to peer-assessment scores, self-assessment scores, and expert assessor scores are analysed. Quality of feedback generated during the peer assessment activity is also considered. An open data set is included within the manuscript and hosted on the Open Science Framework. The results of this study suggest relatively high peer-assessment reliability when compared to expert assessments, although peer scoring tends to be consistently overestimated. In contrast, self-assessment scores demonstrate relatively low reliability when compared with expert assessor scores. The quality of feedback provided during the peer assessment exercise demonstrated a strong relationship with student performance. Recommendations for further refinement and implementation with larger cohorts are discussed.