Comparisons of reliability and validity between teacher-assessment, student self-assessment, and peer-assessment in a web-based portfolio assessment environment

This study compares the reliable and validity among instructor assessment, student self-assessment and peer-assessment under the Web-based portfolio assessment environment. The research samples consist of 72 students who take "Computer Application" course of the second grade in some vocational high school. The students use the Web-based portfolio assessment system for creating their portfolio, emulating peers' portfolio, and performing selfassessment and peer-assessment. The teacher uses the system for reviewing and assessing students' learning performances. In regard to the difference among the three assessment approaches, there exists a significant difference among the three approaches. Instructor assessment is most rigorous, while peer-assessment is most slack. In regard to the correlation among the three assessment approaches, there exists a significant consistency between selfassessment and instructor assessment. There exist inconsistencies between self-assessment and peer-assessment as well as peer-assessment and instructor assessment. In regard to the correlation among the three assessment results and test score, there exist a high consistency between instructor assessment and test score. As well, there exist a high consistency between self-assessment and test score. However, the consistency between peer-assessment and test score is inadequate.