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Table 1.4‘2 × 2’ table for calculation of diagnostic accuracy parameters

Reference standard positiveReference standard negativeTotal
Test positivea (true positive)b (false positive)a+b
Test negativec (false negative)d (true negative)c+d
Totala+cb+da+b+c+d = N (total number of tests in study)

Sensitivity = a/(a+c), specificity = d/(b+d), PPV = a/(a+b), NPV = d/(c+d)

From: 1, Introduction

Cover of Antenatal Care
Antenatal Care: Routine Care for the Healthy Pregnant Woman.
NICE Clinical Guidelines, No. 62.
National Collaborating Centre for Women's and Children's Health (UK).
London: RCOG Press; 2008 Mar.
Copyright © 2008, National Collaborating Centre for Women’s and Children’s Health.

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