This comprehensive guide examines the four core types of validity—internal, external, construct, and statistical conclusion—that form the foundation for evaluating psychological research and ensuring trustworthy conclusions. It provides precise definitions, detailed explanations of common threats with clinically relevant examples, and practical strategies to strengthen each validity type, making complex psychometric principles accessible for EPPP preparation.
The material also includes guidance on applying these concepts when critically evaluating studies, along with two practice questions and rationales that mirror the exam format, enabling candidates to effectively identify and address validity concerns in research design and application.