FreeCalc sample size estimation Inputs Test sensitivity 0.975 Test specificity 0.995 Population size 1000 Design prevalence 0.1 Diseased elements 100 Analysis method Modified hypergeometric exact Target Type I error 0.05 Target Type II error 0.05 Population threshold for infinite probability formula 10000 Maximum sample size 3200 Results Required sample size: 44 Cut-point number of reactors: 1 Type I error: 0.0494 Type II error: 0.0206 Herd-level sensitivity: 0.9506 Herd-level specificity: 0.9794 Interpretation: If a random sample of 44 units is taken from a population of 1000 and 1 or fewer reactors are found, the probability that the population is diseased at a prevalence of 0.1 is 0.0494. Method: Modified hypergeometric exact Detailed Results 1 1 0.102 0.995 0 0.898 0.005 2 100 0.9989 0.9859 2 0.0011 0.0141 3 2 0.1937 0.99 0 0.8063 0.01 4 3 0.2761 0.9851 0 0.7239 0.0149 5 4 0.3501 0.9801 0 0.6499 0.0199 6 5 0.4167 0.9752 0 0.5833 0.0248 7 6 0.4764 0.9704 0 0.5236 0.0296 8 7 0.5301 0.9655 0 0.4699 0.0345 9 8 0.5784 0.9607 0 0.4216 0.0393 10 9 0.6217 0.9559 0 0.3783 0.0441 11 10 0.6606 0.9511 0 0.3394 0.0489000000000001 12 11 0.3112 0.9987 1 0.6888 0.00129999999999997 13 12 0.3504 0.9984 1 0.6496 0.00160000000000005 14 13 0.3889 0.9981 1 0.6111 0.00190000000000001 15 14 0.4264 0.9978 1 0.5736 0.00219999999999998 16 15 0.4626 0.9975 1 0.5374 0.00249999999999995 17 16 0.4975 0.9971 1 0.5025 0.00290000000000001 18 17 0.531 0.9968 1 0.469 0.00319999999999998 19 18 0.5629 0.9964 1 0.4371 0.00360000000000005 20 19 0.5932 0.996 1 0.4068 0.004 21 20 0.622 0.9955 1 0.378 0.00449999999999995 22 21 0.6492 0.9951 1 0.3508 0.00490000000000002 23 22 0.6748 0.9946 1 0.3252 0.00539999999999996 24 23 0.6989 0.9941 1 0.3011 0.00590000000000002 25 24 0.7216 0.9936 1 0.2784 0.00639999999999996 26 25 0.7428 0.9931 1 0.2572 0.00690000000000002 27 26 0.7626 0.9925 1 0.2374 0.00749999999999995 28 27 0.7811 0.9919 1 0.2189 0.0081 29 28 0.7983 0.9913 1 0.2017 0.00870000000000004 30 29 0.8143 0.9907 1 0.1857 0.00929999999999997 31 30 0.8292 0.9901 1 0.1708 0.00990000000000002 32 31 0.843 0.9894 1 0.157 0.0106000000000001 33 32 0.8558 0.9888 1 0.1442 0.0112 34 33 0.8677 0.9881 1 0.1323 0.0119 35 34 0.8787 0.9874 1 0.1213 0.0125999999999999 36 35 0.8888 0.9867 1 0.1112 0.0133 37 36 0.8981 0.9859 1 0.1019 0.0141 38 37 0.9068 0.9852 1 0.0932 0.0148 39 38 0.9147 0.9844 1 0.0853 0.0155999999999999 40 39 0.922 0.9836 1 0.078 0.0164 41 40 0.9287 0.9828 1 0.0713 0.0172 42 41 0.9349 0.982 1 0.0651 0.018 43 42 0.9406 0.9811 1 0.0594 0.0189 44 43 0.9458 0.9803 1 0.0542 0.0197 45 44 0.9506 0.9794 1 0.0494 0.0206