CDTL    Publications     Mailing List     About Brief



People within the educational community—policymakers, schools, administrators, teachers and students—use assessments for different purposes. This issue of CDTL Brief presents some discussions on the issues surrounding Assessment.

March 2003, Vol. 6, No. 3 Print Ready ArticlePrint-Ready
Implementing Effective Peer Assessment
Lim Yuen Lie, Lisa-Angelique
Research Assistant, CDTL

Peer assessment refers to students’ critical evaluations of peers’ performance, whether for writing, oral or visual presentations. Peers may be evaluated in terms of their contribution to the group, their product, or both. When effectively implemented, peer assessment promotes critical thinking and learner autonomy (Race, 2001; Zariski, 1996), both desired characteristics of life-long learners which Singapore aims to cultivate in its graduates (Lim & Chan, 2000; Poh, 1999). Please refer to Race (2001) and Dochy, et al. (1999) for more thorough reviews on the topic.

This article highlights possible difficulties in implementing peer assessment and suggests practical solutions to facilitate effective peer assessment.

Setting up Peer Assessment

To promote effective peer assessment, several issues must be addressed:

  1. Validity & Reliability

    Some problems of validity and reliability include:

    1. Peer over-marking, where peers tend to give higher marks than would tutors (Falchikov, 2002; MacKenzie, 2000; Roach, 1999);

    2. Too wide a range of marks such that tutors have to moderate the marks for the whole class (Bostock, 2000); and

    3. Too narrow a range of marks, making it difficult to differentiate between good, average and weak performers (Cheng & Warren, 1999; MacKenzie, 2000; Zariski, 1996).

    The problems listed above are attributable to students’ inexperience and lack of confidence in marking (Hanrahan & Isaacs, 2001). Practising and exposing students to the peer marking procedure regularly can improve its validity and reliability. Time-conscious educators could model the marking process first, highlighting their rationale along the way, so that students can understand the thought processes behind the marking and apply them to their own peer-evaluations.

  2. Development & Use of Criteria

    Related to the issues of validity and reliability, unsuitable or misused criteria can also invalidate assessment. These problems more likely occur when criteria are simply given to students beforehand; if students themselves do not consider what is important in grading a piece of work, they tend to use the criteria less thoughtfully (Bostock, 2000). Even mere discussion of the criteria does not seem as effective as getting students to develop them independently (Zariski, 1996).

    There are two suggested solutions:

    1. Get students to first work out suitable criteria for assessment, and train them to apply the benchmarks through analysing and discussing their own answers to sample questions (Stanton, 1999), or the work of their predecessors (Smith, Cooper, & Lancaster, 2002). Students are compelled to exercise their critical thinking skills by generating criteria.

    2. Clear and objective criteria will enable students to mark their peers’ work more confidently (Purchase, 2000). Race (2001:Appendix 1) suggests that students reduce obscurity of assessment criteria by employing simple language, and formulating them in terms of checklist questions. For instance, students could re-phrase the criterion, ‘Provides clarity in illustrations’, as ‘How clearly were illustrations given?’, to increase precision in peer-judgments.

    Making students develop their own criteria helps them analyse and think critically as they methodically assess and evaluate a piece of work to determine good and bad qualities. Criteria setting is an essential stage in the peer assessment process if the benefits of critical thinking are to be maximised.

  3. Level of Formality

    Level of formality refers to the accountability of the assessment done by peers: to what extent and how peer-given marks would be included in students’ final course results.

    1. Formative, not summative

      Formative assessment focused on suggesting improvements is preferred to summative assessment that is done solely for computing final marks. This aspect also increases student acceptance of this assessment process, as the direct benefits are concrete (Falchikov, 2002). Not only would students have a chance to improve on their work before submission for a final grade, tutors also benefit from receiving work that has been fine-tuned, removing some of the tedium in marking.

    2. Negotiate, not negate

      Tutors should not override peer marks but strive to use peer marking as an opportunity for negotiating differing peer opinions. There would probably be concerns over the implications of ‘significant outliers’ in cases where a peer-given mark is arbitrated because it differed significantly from the average of the marks given by other groups (Purchase, 2000), or from the tutor-given mark (Lim & Chan, 1999). However, it is interesting that marks given by peers are mostly consistent with the tutor’s marks. Lim and Chan (1999) attribute this to the fact that criteria were discussed and made explicit to students, which again highlights the importance of students’ active engagement in generating marking criteria and understanding how to apply them in critical evaluations. Should significant outliers appear, students should discuss with the tutor and the class why they choose to allocate a certain mark. Such discussions would allow tutors to give useful feedback on students’ thought processes.

      The tutor’s involvement as arbitrator instils in students a sense of accountability in peer assessment, with the assurance that the tutor will be there to ensure fairness of given marks. More importantly, by having to account for the marks given, students are again engaged in critical thinking and learning to verbalise their arguments.

    3. Contribution, not content

      Since fellow group members are probably in the best position to judge individual contributions, peers could assess each other’s contributions to the group, leaving the assessment of product content to the tutor. The individual then gets an overall mark based on some weighted combination of both marks (Crockett & Peter 2002; Crowe & Pemberton, 2000). Weighting procedures can also counter different peer-marker scenarios, for example, those who are overgenerous, and those who ‘conspire’ to penalise a member (Li, 2001).

    To conclude this section, given that the issue of marks is a sensitive one, it is best for tutors to still be involved in mark determination (Sher 2001), while making students accountable for it. More importantly, both tutors and students should strive to keep their focus on the process of critical evaluation and not on the outcome of the marks.

  4. Student Attitudes Towards Peer Assessment

Peer assessment can be met with negative initial responses from students, such as scepticism, lack of confidence, and fears of being discriminated against by peers (Sher, 2001). Students are also known to argue that peer assessment “is too demanding” (Lapham & Webster, 1999), or that assessment is “the tutor’s job” (Crockett & Peters, 2002; Crowe & Pemberton, 2000). Such responses might manifest in attitudes of hostility or even refusal to participate in the process (Bostock, 2000; Zariski, 1996)!

Although these are initial reactions which students do eventually get over, it helps to inform students early of the rationale and benefits of peer assessment (Crowe & Pemberton, 2000; Hanrahan & Isaacs, 2001) and its formative aspects (Sher, 2001). Most students appreciate feedback so that they can improve on their work before it is actually graded. Additionally, it is important to make the procedure clear to students (Smith, Cooper & Lancaster, 2002). Communication with students also includes discussing assessment criteria and allowing students to discuss and negotiate peer-given marks. Giving students feedback on their feedback (Hanrahan & Isaacs, 2001) helps keep them on track and increases their confidence in the process. Ultimately, students must become actively engaged in the thinking processes to reap the benefits in assessing each other, so that they will be empowered to carry it out more seriously.

Final Recommendations

Peer assessment is an important tool to develop critical thinking and autonomous learning—skills that are valued in today’s society. A possible concern for NUS educators in implementing peer assessment is discovering the most time-efficient way of carrying out this procedure without compromising on its benefits. One suggestion is to use students’ presentations of course topics as a form of peer assessment, integrating assessment with course coverage and getting students actively involved in thinking and learning (Lim & Chan, 1999). Another alternative is to take the assessment part of the procedure out of class-time. Students could perform the actual assessment online, and still be made accountable for it (Bostock, 2000).


Implemented effectively, peer assessment fosters critical thinking. Having raised some possible problems and solutions in this article, it is hoped that tutors and students can focus more on the processes of criteria setting, marking and negotiating stages in the procedure, and work towards effective peer assessment.


Bostock, S. (2000). Computer-Assisted Assessments—Experiments in Three Courses. From Learning Technology website, Keele University. (Last Accessed: 23 December 2002).

Cheng, W. & Warren, M. (1999). ‘Peer and Teacher Assessment of the Oral and Written Tasks of a Group Project’. Assessment & Evaluation in Higher Education, Vol. 24, No. 3, pp. 301–314.

Crockett, G. & Peter, V. (2002). ‘Peer Assessment and Team Work as a Professional Skill in a Second Year Economics Unit’. In Focusing on the Student. Proceedings of the 11th Annual Teaching Learning Forum, 5–6 February 2002. Perth: Edith Cowan University. (Last Accessed: 21 December 2002).

Crowe, C. & Pemberton, A. (2000). ‘But That’s Your Job!: Peer Assessment in Collaborative Learning Projects’. Proceedings of the 3rd Effective Teaching and Learning at University Conference, 9–10 November 2000. Brisbane: University of Queensland. (Last Accessed: 21 December 2002).

Dochy. F.; Segers, M. & Sluijsmans, D. (1999). ‘The Use of Self-, Peer and Co-assessment in Higher Education: a Review’. Studies in Higher Education, Vol. 24, No. 3, pp. 331–350.

Falchikov, N. (2002). ‘Unpacking’ Peer Assessment’. In P. Schwartz & G. Webb (Eds.). Assessment: Case Studies, Experience & Practice from Higher Education. London: Kogan Page.

Gregory, A. & Yeomans, L. (2002). Peer Assessment and Enhancing Students’ Learning. Leeds Metropolitan University. (Last Accessed: 23 December 2002).

Hanrahan, S.J. & Isaacs, G. (2001). ‘Assessing Self- and Peer-assessment: the Students’ Views’. Higher Education and Development, Vol. 20, No. 1, pp. 53–70.

Jordan, S. (1999). ‘Self-Assessment & Peer-Assessment’. In Brown, S. & Glasner, A.(Eds.), Assessment Matters in Higher Education. Buckingham [England]; Philadelphia, PA: Society for Research into Higher Education & Open University Press. pp. 172–182.

Lapham, A. & Webster, R. (1999). ‘Peer Assessment of Undergraduate Seminar Presentations: Motivations, Reflection and Future Directions’. In Assessment Matters in Higher Education. Buckingham [England]; Philadelphia, PA: Society for Research into Higher Education & Open University Press. pp. 183–190.

Li, L.K.Y. (2001). ‘Some Refinements on Peer Assessments of Group Projects’. Assessment & Evaluation in Higher Education. Vol. 26, No. 1, pp. 5–18.

Lim, L. & Chan, S. (2000). ‘Practical Ways to Develop Lifelong Learning Skills in SP Students’. Journal of Teaching Practice, Singapore Polytechnic. (Last Accessed: 21 December 2002).

MacKenzie, L. (2000). ‘Occupation Therapy Students as Assessors in Viva Examinations’. Assessment & Evaluation in Higher Education, Vol. 25, No. 2, pp. 135–147.

Poh, S.H. (1999). ‘Assessment Issues in Singapore’. Educational Measurement: Issues and Practice, Vol. 18, No. 3, pp. 31–32.

Purchase, H.C. (2000). ‘Learning About Interface Design Through Peer Assessment’. Assessment & Evaluation in Higher Education, Vol. 25, No. 4, pp. 341–352.

Race, P. (2001). A Briefing on Self, Peer and Group Assessment. Assessment Series No. 9. The Generic Centre, Learning and Teaching Support Network. (Last Accessed: 21 December 2002).

Roach, P. (1999). ‘Using Peer Assessment and Self-Assessment for the First Time’. In Assessment Matters in Higher Education. Buckingham [England]; Philadelphia, PA: Society for Research into Higher Education & Open University Press. pp. 191–201.

Smith, H.; Cooper, A. & Lancaster, L. (2002). ‘Improving the Quality of Undergraduate Peer Assessment: A Case for Student and Staff Development’. Innovations in Education and Teaching International, Vol. 39, No. 1, pp. 71–81.

Sher, W. (2001). Peer Assessment in the Design & Construction of a Reinforced Concrete Lintel. From Assessment Case Studies in the Centre for Education in the Built Environment website. Loughborough University. (Last Accessed: 21 December 2002).

Stanton, K. (1999). ‘Involving Students in Setting Criteria for Assessing Written Work’. In Hinett, K. & Thomas, J. (Eds.). Staff Guide to Self and Peer Assessment. Oxford: Oxford Brookes University. pp. 51–53.

Zariski, A. (1996). ‘Student Peer Assessment in Tertiary Education: Promise, Perils & Practice’. In Abbott, J. & Willcoxson, L. (Eds.), Teaching and Learning Within and Across Disciplines, pp. 189–200. The Proceedings of the 5th Annual Teaching Learning Forum. Murdoch University. (Last Accessed: 21 December 2002).

 First Look articles

Search in
Email the Editor
Inside this issue
Assessing Education Quality: Measures and Processes
Addressing Students’ Fears about Examinations
Student Assessment in Problem-based Learning: A Challenge Beyond Reliability and Validity
Implementing Effective Peer Assessment
Self-and Peer-assessments — Vehicles to Improve Learning
What is Quality in Assessment Practice?