This indicator casts a wide net to measure equity, as it is meant to be applied to all other SDG 4 indicators with available data, and measures equity over a range of dimensions (such as gender, socio-economic status and location). In particular, it enables the same indicator to be analysed across multiple equity dimensions. For example, applying Global indicator 4.5.1 to Global Indicator 4.1.1 shows that students’ ability to perform at least at PISA level 2 in mathematics is relatively weakly associated to their gender, but remains strongly determined by the location of students' schools (rural or urban) in the majority of OECD and partner countries, and by socio-economic status as measured by the PISA index of economic, social and cultural status (ESCS1) in all OECD and partner countries (Figure 2). For example, measuring the gender parity index associated with SDG 4 indicators confirms that students' gender does not influence children’s participation in education one year before the primary entry age (SDG 4.2.2) in all OECD countries, and is weakly associated with the ability of 15-year-old students to perform at least at PISA Level 2 in mathematics (SDG 4.1.1).