Appendix 1

The table lists sample calculations to illustrate the effect of variation in reference test sensitivity and specificity on diagnostic test sensitivity. The calculations assume a disease prevalence of 0.1, a true diagnostic test sensitivity of 0.9, and a true diagnostic test specificity of 0.9. The cells show apparent diagnostic test sensitivity for a given reference test specificity (rows) and reference test sensitivity (columns).

Sensitivity / 0.10 / 0.20 / 0.30 / 0.40 / 0.50 / 0.60 / 0.70 / 0.80 / 0.90 / 0.95 / 0.99 / 1.00
Specificity
0.10 / 0.110 / 0.119 / 0.129 / 0.138 / 0.147 / 0.155 / 0.164 / 0.172 / 0.180 / 0.184 / 0.187 / 0.188
0.20 / 0.111 / 0.122 / 0.132 / 0.142 / 0.152 / 0.162 / 0.171 / 0.180 / 0.189 / 0.193 / 0.197 / 0.198
0.30 / 0.113 / 0.125 / 0.136 / 0.148 / 0.159 / 0.170 / 0.180 / 0.190 / 0.200 / 0.205 / 0.209 / 0.210
0.40 / 0.115 / 0.129 / 0.142 / 0.155 / 0.168 / 0.180 / 0.192 / 0.203 / 0.214 / 0.220 / 0.224 / 0.225
0.50 / 0.117 / 0.134 / 0.150 / 0.165 / 0.180 / 0.194 / 0.208 / 0.221 / 0.233 / 0.239 / 0.244 / 0.245
0.60 / 0.122 / 0.142 / 0.162 / 0.180 / 0.198 / 0.214 / 0.230 / 0.245 / 0.260 / 0.267 / 0.273 / 0.274
0.70 / 0.129 / 0.155 / 0.180 / 0.203 / 0.225 / 0.245 / 0.265 / 0.283 / 0.300 / 0.308 / 0.315 / 0.316
0.80 / 0.142 / 0.180 / 0.214 / 0.245 / 0.274 / 0.300 / 0.324 / 0.346 / 0.367 / 0.376 / 0.384 / 0.386
0.90 / 0.180 / 0.245 / 0.300 / 0.346 / 0.386 / 0.420 / 0.450 / 0.476 / 0.500 / 0.511 / 0.519 / 0.521
0.95 / 0.245 / 0.346 / 0.420 / 0.476 / 0.521 / 0.557 / 0.587 / 0.612 / 0.633 / 0.643 / 0.650 / 0.652
0.99 / 0.521 / 0.652 / 0.715 / 0.753 / 0.778 / 0.796 / 0.809 / 0.819 / 0.827 / 0.831 / 0.833 / 0.834
1.00 / 0.900 / 0.900 / 0.900 / 0.900 / 0.900 / 0.900 / 0.900 / 0.900 / 0.900 / 0.900 / 0.900 / 0.900

Appendix 2

The table lists sample calculations to illustrate the effect of variation in reference test sensitivity and specificity on diagnostic test specificity. The calculations assume a disease prevalence of 0.1, a true diagnostic test sensitivity of 0.9, and a true diagnostic test specificity of 0.9. The cells show apparent diagnostic test specificity for a given reference test specificity (rows) and reference test sensitivity (columns).

Sensitivity / 0.10 / 0.20 / 0.30 / 0.40 / 0.50 / 0.60 / 0.70 / 0.80 / 0.90 / 0.95 / 0.99 / 1.00
Specificity
0.10 / 0.500 / 0.524 / 0.550 / 0.580 / 0.614 / 0.654 / 0.700 / 0.755 / 0.820 / 0.858 / 0.891 / 0.900
0.20 / 0.633 / 0.654 / 0.676 / 0.700 / 0.726 / 0.755 / 0.786 / 0.820 / 0.858 / 0.878 / 0.896 / 0.900
0.30 / 0.700 / 0.717 / 0.735 / 0.755 / 0.775 / 0.797 / 0.820 / 0.845 / 0.871 / 0.885 / 0.897 / 0.900
0.40 / 0.740 / 0.755 / 0.770 / 0.786 / 0.802 / 0.820 / 0.838 / 0.858 / 0.878 / 0.889 / 0.898 / 0.900
0.50 / 0.767 / 0.779 / 0.792 / 0.806 / 0.820 / 0.835 / 0.850 / 0.866 / 0.883 / 0.891 / 0.898 / 0.900
0.60 / 0.786 / 0.797 / 0.808 / 0.820 / 0.832 / 0.845 / 0.858 / 0.871 / 0.885 / 0.893 / 0.899 / 0.900
0.70 / 0.800 / 0.810 / 0.820 / 0.830 / 0.841 / 0.852 / 0.864 / 0.875 / 0.888 / 0.894 / 0.899 / 0.900
0.80 / 0.811 / 0.820 / 0.829 / 0.838 / 0.848 / 0.858 / 0.868 / 0.878 / 0.889 / 0.894 / 0.899 / 0.900
0.90 / 0.820 / 0.828 / 0.836 / 0.845 / 0.853 / 0.862 / 0.871 / 0.881 / 0.890 / 0.895 / 0.899 / 0.900
0.95 / 0.824 / 0.822 / 0.839 / 0.848 / 0.856 / 0.864 / 0.873 / 0.882 / 0.891 / 0.895 / 0.899 / 0.900
0.99 / 0.827 / 0.822 / 0.842 / 0.850 / 0.857 / 0.866 / 0.874 / 0.882 / 0.891 / 0.896 / 0.899 / 0.900
1.00 / 0.827 / 0.835 / 0.842 / 0.850 / 0.858 / 0.866 / 0.874 / 0.883 / 0.891 / 0.896 / 0.899 / 0.900