Fig. 1
From: The validity of the SF-12 and SF-6D instruments in people living with HIV/AIDS in Kenya
The PCS and SF-6D ROC curves when comparing WHO stage one to more advanced stages. Caption: The area under the ROC curve (AUC) is a measure of signal to noise of an instrument. The signal appears to improve as the severity gap between the comparison groups increases. This indicates discriminatory ability of both survey scores and gives face validity to them since the survey is correctly measuring what it was designed to measure