Scaling Success: A Systematic Review of Peer Grading Strategies for Accuracy, Efficiency, and Learning in Contemporary Education

TL;DR

This systematic review analyzes 122 studies on peer grading, proposing a taxonomy to improve accuracy, fairness, and learning outcomes, and highlights the potential of hybrid strategies for effective assessment in large educational settings.

Contribution

The paper introduces a comprehensive taxonomy of peer grading systems and evaluates their impact on assessment quality, providing a practical framework for designing better peer assessment methods.

Findings

Formative feedback is rarely used as a weighting factor.

No single weighting strategy is universally best.

Hybrid strategies show the most promise.

Abstract

Peer grading has emerged as a scalable solution for assessment in large and online classrooms, offering both logistical efficiency and pedagogical value. However, designing effective peer-grading systems remains challenging due to persistent concerns around accuracy, fairness, reliability, and student engagement. This paper presents a systematic review of 122 peer-reviewed studies on peer grading spanning over four decades. Drawing from this literature, we propose a comprehensive taxonomy that organizes peer grading systems along two key dimensions: (1) evaluation approaches and (2) reviewer weighting strategies. We analyze how different design choices impact grading accuracy, fairness, student workload, and learning outcomes. Our findings highlight the strengths and limitations of each method. Notably, we found that formative feedback -- often regarded as the most valuable aspect of peer assessment -- is seldom incorporated as a quality-based weighting factor in summative grade synthesis techniques. Furthermore, no single reviewer weighting strategy proves universally optimal; each has its trade-offs. Hybrid strategies that combine multiple techniques could show the greatest promise. Our taxonomy offers a practical framework for educators and researchers aiming to design peer grading systems that are accurate, equitable, and pedagogically meaningful.