Abstract
This seminar introduces international large-scale assessment research through two influential studies: the Programme for International Student Assessment (PISA) and the Trends in International Mathematics and Science Study (TIMSS). We explore what these assessments measure, why their designs differ, and how researchers use carefully selected samples, questionnaires, and statistical methods to investigate patterns across countries and over time. These rich datasets offer opportunities to study student achievement, engagement with science, learning opportunities, educational inequality, and pathways into further science education.

At the same time, international comparisons require careful interpretation. We consider whose knowledge is represented, whether questions have comparable meanings across cultures, who may be excluded from the data, and why statistical relationships do not necessarily demonstrate causation. No advanced statistical background is required. The seminar introduces the main ideas in accessible terms and considers how large-scale evidence could contribute to astronomy education research.

By the end of this seminar, participants will be able to:
• Explain the main purposes and designs of international large-scale assessments
• Describe opportunities for using large-scale assessment data in education research
• Recognise key methodological challenges and interpret findings from these assessments critically

Glossary terms:
• International large-scale assessment (ILSA)
• Programme for International Student Assessment (PISA)
• Trends in International Mathematics and Science Study (TIMSS)
• Representative sample
• Plausible values
• Cross-national comparability
• Multilevel analysis

Abstract
Surveys are widely used to measure attitudes, perceptions, experiences and other constructs that cannot be observed directly. However, developing a questionnaire that produces meaningful and interpretable data involves considerably more than writing a set of Likert-scale questions. This session will explore the process of designing and validating quantitative survey instruments, drawing on practical examples from research developing measures of students' attitudes towards astronomy and science, and experiences of inclusion in science engagement.

This webinar will consider how to move from defining a construct to developing appropriate survey items, including the use of existing literature and instruments, expert review, cognitive testing, and piloting. Key quantitative approaches to evaluating instruments will be reviewed, including item analysis, internal consistency and reliability, and exploratory and confirmatory factor analysis. The session will then discuss complimentary qualitative approaches to evaluating the appropriateness and effectiveness of survey instruments.

Rather than treating validation as a single statistical test, the session will emphasise validation as an ongoing process of accumulating evidence about whether an instrument supports the interpretations researchers wish to make from its scores. Participants will leave with a foundation for validating their own surveys, with practical examples, and an overview of common pitfalls and limitations.

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