Secondary studies synthesise the results from primary studies: Systematic reviews have a defined set criteria for finding and including primary studies for critical analysis. Methodology from these primary studies is often evaluated and results synthesised. Meta-analysis is a statistical procedure for combining quantitate data from studies evaluating the same outcomes (e.g. data from a study of a large population showing a strong correlation and data … Continue reading Secondary studies

Diagnostic and screening tests (e.g. HIV blood test, colonoscopy) respectively confirm a condition or detect high risk individuals. Measures such as sensitivity and predictive values are used describe these tests. They can help calibrate tests (e.g. set criteria for positive diagnosis) or indicate the suitability of tests to different applications (i.e. a less accurate but cheaper test may be more suited to screening than diagnosis). … Continue reading Diagnostic & screening tests

Observational (or non-experimental) studies have no intervention and purely observe changes in one characteristic (e.g. smoking) compared to another (e.g. lung cancer) in the natural world. These studies can be classed into analytical studies, which aim to determine correlation and causality, or descriptive which merely reports a certain situation. Analytical studies Analytical (analytic) studies examine populations and analyze if there is a causal correlation between … Continue reading Observational studies