Bayes and likelihoodratio

Sunday, November 24th, 2013

In their diagnostic process, GPs combine large amounts of knowledge they have accumulated during their personal training. They consider illness scripts or prototypes, which they then accept or reject. At the same time, considering diagnostic data also implies a quantitative process, namely assessing the probability that the patient has a particular disease. Thomas Bayes (1702-1761) formulated in mathematical terms how the probability of a particular conclusion – in medicine a diagnosis – is altered by new data that become available, for instance from history-taking or examination. Bayesian logic can be described as a mathematical rule combining prior information with evidence from data.(1;2) read more

Medical Decision-Making and Medical Problem Solving

Tuesday, May 14th, 2013

Medical Decision Making and Medical Problem Solving are two main approaches used to describe the cognitive processes underlying clinical diagnosis.(1) This distinction is the result of historical factors. A diagnosis is a statement about what disease someone has ( based on symptoms (subjectively) and signs (objectively).(2) Medical decision making (MDM) models are concerned with diagnostic reasoning as an opinion revision process.(3) They make use of Bayes’ theorem, likelihood ratios, prior and posterior odds, thresholds, schemes and decision trees to arrive at the best diagnostic and therapeutic decisions. (1;3-7) These mathematical models, incorporating clinical epidemiological data, are related to the concept of evidence-based medicine. read more