Statistical Terms
Pre-Test Probability
Pretest Probability is defined as the probability of the target disorder before a diagnostic test result is known.
Likelihood Ratios
The Likelihood Ratio (LR) is the likelihood that a given test result would be expected in a patient with the target disorder compared to the likelihood that that same result would be expected in a patient without the target disorder.
Numbers Needed to Treat
The Number Needed to Treat (NNT) is the number of patients you need to treat to prevent one additional bad outcome (death, stroke, etc.).
SpPins and SnNouts
SpPin
When a sign, test or symptom has an extremely high specificity (say, over 95%), a positive result tends to rule in the diagnosis.
SnNout
When a sign, test or symptom has a high sensitivity, a negative result rules out the diagnosis.