Measuring planetary health knowledge: Development and psychometric evaluation of a taxonomy-based test

Planetary Health Knowledge (PHK) refers to knowledge about global conditions and interrelations between the health of the planet, human health, and human civilization. In times of various humanitarian and environmental crises, knowledge about and awareness of these problems become increasingly important. This is reflected in the Sustainable Development Goals and various Global Citizenship Education programs that emphasize the importance of knowledge about global challenges as a key characteristic in promoting sustainability. Despite its relevance, a comprehensive, psychometrically evaluated measure of PHK is currently lacking. Based on the recently proposed PHK Taxonomy, we developed a comprehensive PHK item pool of approximately 500 knowledge items targeting knowledge about global issues in seven domains: Health, Nutrition, Environment, Safety, Education, Standard of Living, and Political & Economic systems. The item pool was evaluated in seven domain-specific psychometric studies using a balanced-incomplete-block-design, administered to a total of N = 2204 participants. Items suitable for general population samples were selected based on psychometric characteristics. Construct validity was examined via associations with general knowledge (gc), global citizenship identification (GCI), sustainable behavior, educational attainment, subjective knowledge, information seeking frequency, and party affiliation. Across all domains, PHK showed moderate to strong associations with gc (r = .539 - .736) and educational attainment, and weaker associations with GCI (r = .238 - .416). Associations with sustainable behavior, subjective knowledge, and information seeking-frequency were small to negligible. The resulting domain-specific PHK item sets provide psychometrically evaluated PHK measures for assessing PHK in general population samples. Finally, we discuss implications for knowledge assessment and future applications in research and evaluation.