Correction


The value of the negative predictive values (Correspondence)

In the table submitted with a letter to the Editor (Vol 106, December 1999, pp. 1331–1332) the confidence intervals corresponding to Helin et al.'s PPV of 12/31 should have read 0.22–0.56 for the simple method and 0.2–0.56 for the better method (not 0.94–1.00 for the simple method and 0.92–0.986 for the better method as published).

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