The row ratios are Positive Predictive Value ( PPV , aka precision ) ( TP / ( TP + FP ) ) , with complement the FALSE Discovery Rate ( FDR ) ( FP / ( TP + FP ) ) ; and Negative Predictive Value ( NPV ) ( TN / ( TN + FN ) ) , with complement the FALSE Omission Rate ( FOR ) ( FN / ( TN + FN ) ) .