Sensitivity+and+specificity

Sensitivity = TP/(TP+FN) Specificity = TN/(TN+FP)

Table Condition: Condition Positive Condition Negative Test Outcome Positive TP FP Negative FN TN

Mneumonics for sensitivity and specificity http://books.google.com/books?id=HW0hr7c5l8MC&pg=PA219&lpg=PA219&dq=how+can+i+remember+the+difference+between+sensitivity+and+specificity&source=bl&ots=pHYR7sL1RX&sig=go-9Hy7IARwHVWCgYREluHTHmG8&hl=en&sa=X&ei=5iQEUeydE6XUiwLdnIDQAw&ved=0CEEQ6AEwAQ#v=onepage&q=how%20can%20i%20remember%20the%20difference%20between%20sensitivity%20and%20specificity&f=false http://forums.studentdoctor.net/archive/index.php/t-125098.html

SeNsitive tests are Negative in health (NIH) SPecific tests are Positive in Disease (PID)

Sensitivity: SnOut- sensitive tests rule out diesease - meaning that on a test with high sensitivity if you test negative chances are you don't have the disease (screening). If you rule disease out this means you have few false negatives. Specificity: SpIn- specific tests rule in disease - meaning that on a test w. high specificity if you test positive chances are you got the disease (confirmatory). If you rule disease in this means you have few false positives.

SeNsitivity includes False Negatives SPecificity includes False Positives

Note that a ROC curve has true positives vs false positives (1-specificity)