Evidence type
Evidence types
Understand evidence types used in health and science reporting, from lab studies to trials, and what each can and cannot prove.
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Animal studies
Animal studies can provide valuable insights into biological processes and potential effects of interventions. However, results from animal experiments may not translate to humans. This page explains why animal research can inform but not confirm health claims about people.
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Cell studies
How in-vitro and cell-line findings should be interpreted in health headlines. Cell studies investigate the effects of substances or genetic changes in isolated cells outside the human body. While these studies can show how something may work at a basic biological level, their results do not directly apply to human health without further research.
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Observational studies
Observational studies look for associations in real-world populations but do not automatically prove that one factor causes another. Other explanations—including confounding and reverse causation—are important to consider when interpreting their results.
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Randomised trials
Randomised trials are a key method for testing the effects of medical and health interventions. By randomly assigning participants, these studies aim to balance differences between groups and reduce bias, making their findings more reliable. However, they are not free from limitations, and careful interpretation is still needed.
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Systematic reviews
Systematic reviews summarise multiple studies using transparent, pre-specified methods. Their strength as evidence depends not only on their process but also on the quality and relevance of the included studies.
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Guidelines
Guidelines translate research evidence into recommendations for clinical practice, but their strength can vary depending on the available evidence, expert interpretation, and other practical factors.