This handbook provides answers to questions such as "What is a teacher?", "What do we mean by public education expenditure?" as well as questions concerning the use of the indicators "How should I interpret expenditure per student?" "What is it measuring?". In so doing, the handbook aims to facilitate a greater understanding of the OECD statistics and indicators produced and so allow for their more effective use in policy analysis. Equally, it provides a ready reference of international standards and conventions for others to follow in the collection and assimilation of educational data. This publication describes the methodology used in the International Survey of Upper Secondary Schools(ISUSS) and in related OECD publications and allows researchers to understand and replicate its analyses.