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. 1997 Aug;12(8):500–504. doi: 10.1046/j.1525-1497.1997.00089.x

Figure 1.

Figure 1

The effect of the prior likelihood of a disease on the ability of a test to predict its presence in a patient. It is assumed that 90% of patients with lupus and 5% of patients without lupus will have a positive ANA test. (A) The ability of a positive ANA test to predict the presence of lupus in a population with a low likelihood of the disease (1% of patients have lupus). (B) The predictive ability of a positive ANA test in a population with a high likelihood of the disease (50% of patients have lupus).