Numerous diagnostic tests exist that can provide information to guide medical decision making. In a broad sense, diagnostic tests include symptoms and signs (e.g., chest pain, fatigue, varicose veins, ankle edema); measurements on physical examination (e.g., height, weight, blood pressure); special measurements (e.g., ankle-brachial pressure index, electrocardiogram [ECG], electroencephalogram [EEG]); blood tests (e.g., cholesterol, lipid profile, glucose); cytology and histology (e.g., Papanicolaou smears, biopsy); and imaging tests (e.g., endoscopy, ultrasound, computerized tomography [CT], magnetic resonance imaging [MRI], [Page 383]single photon emission computed tomography [SPECT], positron-emission tomography [PET]).

Tests results can be dichotomous—that is, the result is either positive or negative, or the test may have multiple possible results on a categorical, ordinal, or continuous scale. Interpreting information obtained from diagnostic tests correctly is key in optimizing ...