TableĀ 1

Cross classification of index test and reference standard results

Reference standard positiveReference standard negativeTotal
Index test positivea (true positives)b (false positives)a+b (test positives)
Index test negativec (false negatives)d (true negatives)c+d (test negatives)
Totala+c (disease positives)b+d (disease negatives)a+b+c+d (study total)