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Choosing Cut-Offs in Tests
My last blog post was on the difference between Sensitivity, Specificity and the Positive Predictive Value. While showing that a positive test result can represent a low probability of actually having a trait or a disease, this example used the values of Sensitivity and Specificity as pre-known input. For established tests and measures they indeed…
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Visualizing Sensitivity and Specificity of a Test
In my university course on Psychological Assessment, I recently explained the different quality criteria of a test used for dichotomous decisions (yes/no, positive/negative, healthy/sick, …). A quite popular example in textbooks is the case of cancer screenings, where an untrained reader might be surprised by the low predictive value of a test. I created a…