This research explored the effect of incentives to complete online quizzes during a course. When a 1% weighting incentive per quiz was removed, student engagement dropped dramatically. There is also evidence that students who continued to complete quizzes did so with less vigour, spending less time on each quiz, starting them later in the week and having fewer attempts per quiz on average. The average mark per quiz was also lower once an incentive to complete them was removed. There was no significant difference in examination performance based on how many quizzes a student continued to attempt after incentives were removed. However, a comparison to a control group of students who sat the same invigilated assessments showed that, relative to term test performance, final exam mean score was 7% lower for the cohort who had the incentive to complete online quizzes removed. This differed from the control group, who showed no difference between term test and final examination mean scores when quiz incentives were maintained for the entire course. Building on previous research, this study demonstrates that a binary variable representing engagement in online quizzes did not capture the quality of that online engagement.