What is intra-group?
Cross-assessment
Peer assessments providing feedback on a production, assignment or performance.
Intra-group valuation
Peer evaluations giving feedback on the attitude, work processes of group members.
The educational benefits of the method

Points to consider
There are a number of issues to consider in applying the method so that students can fully benefit from these advantages.

Define the purpose of the evaluation
Is it purely formative or does it also have a summative purpose? With this method, one can match the grade that a group has achieved to the investment of each individual in a group - based on their perceived investment by their peers. By doing this, the perception of fairness through shared effort will be reinforced, which will increase students' satisfaction and investment in the process.

Preceded the evaluation by a group meeting
By holding a meeting between students before the intra-group evaluation, a more consensual and therefore more valid evaluation is achieved.

Integrate a self-assessment
By including a self-evaluation - an evaluation of one's own investment in the group - in the evaluation, a more valid evaluation is obtained.

Group size
The evaluation will be better if the number of people in a group corresponds to the standards in education, i.e. 4 or 5 people maximum.

Feedback
Scheduling an intra-group assessment in the middle of an activity allows students to take feedback from their group mates, which improves performance and reduces the number of free riders detected by an intra-group assessment at the end of the activity.
Defining an evaluation method
As with all other forms of valuation, the quality of the intra-group valuation will depend to a large extent on the method used to value. There are two methods for this: holistic - global - and criterion-referenced valuation.
The criterion-referenced method
The preferred method for its completeness and validity will be the criterion-based method. To do this, it is either possible to co-construct the grid with the students in order to increase their investment, or to use a valid grid to evaluate the attitude of the students in the group work.
The holistic method
The simple holistic evaluation, i.e. giving a global appreciation of the attitude, of the investment of a peer in a group, is an invalid method. Nevertheless, it is possible to attach indicators, so this method will be more valid and formative.

Bibliography :
1 Elliott, N., & Higgins, A. (2005). Self and peer assessment - does it make a difference to student group work? Nurse Education in Practice, 5(1), 40-48. doi:10.1016/j.nepr.2004.03.004
2 Kennedy, G. J. (2005, January). Peer-assessment in group projects: is it worth it? In Proceedings of the 7th Australasian conference on Computing education-Volume 42 (pp. 59-65).
3 Conway, R., Kember, D., Sivan, A., & Wu, M. (1993). Peer assessment of an individual's contribution to a group project. Assessment & Evaluation in Higher Education, 18 (1), 45-56.
4 Kench, P. L., Field, N., Agudera, M., & Gill, M. (2009). Peer assessment of individual contributions to a group project: Student perceptions. Radiography, 15(2), 158-165.d oi:10.1016/j.radi.2008.04.004