TABLE 1.

Diagnostic accuracy terms

True positive (TP)	Individuals with the target condition who receive a positive screening questionnaire result
False positive (FP)	Individuals without the target condition who receive a positive screening questionnaire result
True negative (TN)	Individuals without the target condition who receive a negative screening questionnaire result
False negative (FN)	Individuals with the target condition who receive a negative screening questionnaire result
Sensitivity (se)	The “true positive rate,” that is, the probability that a person with the target condition (e.g., an eating disorder) will receive a positive screening questionnaire result. A sensitivity of 1.0 indicates that the screening questionnaire will identify all individuals with the target condition with no “false negative” results.
Specificity (sp)	The “true negative rate,” that is, probability that a person without the target condition will receive a negative screening questionnaire result. A specificity of 1.0 indicates that all individuals without the target condition will receive a negative screening questionnaire result with no “false positive” results.
Negative predictive value (NPV)	The proportion of people with a negative screening questionnaire result that do not have the target condition
Positive predictive value (PPV)	The proportion of people with a positive screening questionnaire result that have the target condition
Area under the curve (AUC)	AUC refers to the area under a receiver operating characteristics (ROC) curve. This provides a summary of the overall diagnostic accuracy of a test by combining sensitivity and specificity. An AUC of .5 indicates random chance that the test will correctly characterize patients, while an AUC of 1 indicates perfect diagnostic accuracy.

Source: Adapted from Šimundić (2009).