Beyond classical content validity indices: methodological aspects and reporting recommendations for nursing research

Background: Expert panels are widely used in nursing research to judge whether items, definitions or diagnostic components adequately represent a content domain. However, numerical indices for these tasks are often treated as if they all measured the same entity. Aims: To examine classical and less commonly discussed procedures used to summarise expert judgement in content-validation studies. Methods: A narrative methodological review and analytical demonstration used seminal and later methodological sources to address five predefined questions; hypothetical datasets were used only to reproduce and compare the procedures. Findings: The procedures are not interchangeable; while some summarise the proportion of experts endorsing relevance or essentialness, others preserve graded ratings, some adjust a proportion for a chance model and others focus on disagreement, coverage or item-to-domain mapping. Because these procedures transform expert judgements differently, the same ratings can produce different numerical values. Small panels can also produce imprecise estimates even when a point estimate appears favourable. Conclusion: Researchers should choose a procedure because it answers their methodological question. Clear reporting of the target domain, expert task, original ratings, formula, panel size, uncertainty and complementary agreement or reliability information makes content-validation evidence easier to interpret and use.