This paper addresses the question of whether peer collaboration affects students' performance of regression modelling tasks, an experimental study consisting of a test was conducted in a computing laboratory. Collaborating groups of students were randomly assigned to one of three experimental conditions: pre-task discussion (i.e., group members had discussions right at the beginning of the test), post-task (i.e., group members had discussions in the middle of the test) or no discussion. It was found that the influence of the pre-task discussion on a preliminary examination of regression data was not very explicit in accomplishing tasks involving judgement of data reasonableness and meaningfulness, correlation calculation, Excel programming, and statistical hypothesis testing. Yet, students who had pre-task discussion showed better quality in graph construction as well as graph characterization and also performed better in correlation interpretation and reasoning tasks than those who did not. Students could clarify their misunderstanding and/or refine their thoughts through post-task discussion but no improvements in comprehension of data were detected for correlation calculation; Excel programming, hypothesis testing, and correlation deduction as well as synthesis.