How did the NRF come up with the prescribed age restrictions?

The average completion age for an undergraduate degree as published by the Department of Higher Education and Training (DHET) was 21 years. In addition, the NRF analysed a cohort of 60 000 postgraduate students funded by the NRF over a six-year period and looked at the average age at completion for honours, masters and doctoral students. The prescribed ages for qualifications were obtained as an outcome of this analysis.