Franz Wiesbauer looks at the impact of specificity and sensitivity on positive predictive value (and thus validity of a test) and why one has a bigger impact than the other.
Franz Wiesbauer explains how to express prognosis with the help of life tables and why this is essential to understanding Kaplan Meier curves.
Franz Wiesbauer looks at how a doctor can work out the probability of disease when confronted with a positive or a negative test result and how the prevalence of a given disease affects this probability.
Types of study design arranged by level of evidence, from low to high
Retrospective studies are designed to analyse pre-existing data, and are subject to numerous biases as a result. Types of retrospective studies include: case series; retrospective cohort studies; case-control studies