This Chapter turns to the statistics and indicators that are derived from the raw data. It aims to explain the concepts, methodologies and conventions used in the calculation of these statistics and indicators and the measurement issues that arise. The chapter does not seek to describe in detail every indicator that appears or ever has appeared in Education at a Glance (EAG). Instead it focuses on the key indicators or groups of indicators which appear in EAG which have conceptual or methodological aspects which are worthy of explanation; it is a catalogue of indicator methodologies rather than a catalogue of indicators. Thus, indicators which are straightforward summaries of the data items as collected (e.g. the proportion of graduates who are female) are not covered here. In the indicators that are covered, the level of detail ...