This article is the fourth in a series arguing that there is serious mismeasurement of enrolment in early childhood development (ECD) and in the early grades of education systems in many countries, especially, and most damagingly, in those making the most progress on access to schooling and in the sustainable development goals. Other reports have used aggregate data reported to UNESCO, and parent and teacher survey data (specifically compared to school records, in one case) to explain the problems. Mismeasurement is leading to incorrect policy conclusions (related to access and persistence) and is generally too optimistic about ECD-related progress in these countries. This article uses a methodology adapted from similar work in Latin America in the late 1980s and early 1990s, and data on enrolment by age and grade from five African education systems that suffer from mismeasurement. The article argues that grade repetition in the early grades and lack of preprimary opportunities are causing the problem of overenrolment. This analytical approach is relatively novel to these environments and shows that rates of repetition are, most likely, about twice that of official reports. The results from this analysis match the results of the other articles in the series. An important implication is that these issues are undermining the completion of primary schooling, due to weak policies resulting in part from mismeasurement.