Much research has highlighted the factors leading to increasing dropouts among first-year undergraduates around the globe. This phenomenon is also an issue in New Zealand. Therefore, this research estimates the importance of various factors, derived from the administrative data provided by the Department of Strategy and Planning at AUT, on the probability of successful course completion at university. Non-completion of first-year courses may form the basis of future non-retention amongst undergraduate students. Efforts to avoid future substantial costs to the university and the government could prove beneficial by identifying factors that result in successful completion of courses as early as possible. This research focuses on first-year students who entered university using valid NCEA Level 3 scores. Majority of the universities in New Zealand, including AUT, have traditionally summarised NCEA results with a composite ‘rank’ score that arbitrarily assigns weights to Achieved, Merit and Excellence credits without any empirical study supporting the appropriateness of this weighting scheme. This study provides some empirical evidence on the validity of this weighting scheme by estimating the contributions of these different credits in predicting the successful completion of first-year courses. Results from our research also indicate that other factors (e.g., part-time study, gender and the degree programme) may play crucial roles in predicting successful course completion rates. Most importantly, we found that Merit and Excellence credits do not significantly differ in terms of predicting the probability of successful completion of courses. Therefore, we propose an alternative weighting scheme based on this empirical evidence that outperforms the existing NCEA rank score in predicting the successful completion of first-year courses at university.