Importance of socio-economic differences on the probability of repetition at equal skills levels

The odds ratio, i.e. at equal mathematics and science proficiency, how many times higher is the probability of repeating an academic year for a student from a more disadvantaged background compared to a student with more resources. For example, a value of 4 means that, with equivalent skills in mathematics and science, a student with fewer resources (25% of students with fewer resources) is four times more likely to have repeated an academic year than a student from a more favourable background (25% of students with more resources).