Thesis (Ph.D.)--Chulalongkorn University, 2007

The objectives of this study were 1) to compare the effects of paper-pencil peer feedback, e-mail peer feedback and web board peer feedback on the students’ writing achievement and to investigate their effect size; 2) to compare the effects of the levels of general English proficiency (high, moderate and low) on students’ writing achievement and to investigate their effect size; 3) to investigate the interaction effect between the types of peer feedback and levels of general English proficiency on students’ writing achievement and to investigate their effect size; 4) to survey the students’ attitudes toward the peer feedback they experience. The study was conducted with 90 engineering students with different levels of general English proficiency in a 3x3 factorial design. Stratified random sampling technique was used in this study for subject selection. In order to ensure the quality of peer feedback, they were trained for 6 hours on how to give useful feedback. The writing achievement test and close-ended questionnaire were used for the quantitative data collection. Two-way Analysis of Variance (ANOVA) and descriptive statistics were used to analyze and to explain the data. The qualitative data were gathered from open-ended questionnaire, learning log, and interview. The data in this part were transcribed, categorized, analyzed, and then presented in terms of tables and graphs. The findings were as follows: 1) the different types of peer feedback had a significantly different effect on the students’ writing achievement. It was found that the students in the web board group performed differently from the students in paper-pencil peer feedback group while the differences were not found between other pairs. The magnitude of the effect size was medium. 2) The levels of general English proficiency factor had a significant effect on the students’ writing achievement. Students in different ability groups all performed differently. The magnitude of the effect size for this factor was large. 3) There was no interaction effect between types of peer feedback and levels of general English proficiency on the students’ writing achievement. High proficiency students in the three groups performed better than the moderate proficiency students who performed better than the low proficiency ones regardless of the types of peer feedback they received. 4) The attitudes towards peer feedback of the three experimental groups were more or less the same that they had highly positive attitudes in most aspects explored.