A commonly-held belief is that many university students are 'assessment-driven'; that is, students engage more with activities that are assessed compared with those that are not. 'Incentivised engagement' includes the practice of providing incentives (such as marks or otherwise) for students to engage in particular activities. Perusall is a social annotation platform designed to increase student engagement with pre-class reading. In this study, students in a second-year undergraduate Statistics for Engineering module were invited to carry out the weekly reading activity via the Perusall platform. During the first half of the semester, students' engagement via Perusall did not count towards student marks, whereas during the second half of the semester, it did. We present the estimated effect of incentivised engagement, via use of the Perusall platform, on student engagement and performance. Our results show that incentivisation increased the engagement of students who were previously less engaged with the pre-class reading. For those students who were previously less engaged and had lower performance in summative assessments, there was also an increase in student performance following incentivisation. However, this effect was not observed for students who were already performing well before incentivisation.