Appendix Tables

Appendix Tables 273

Table A.t. Random numbers arranged in groups of 5 digits

85967 73152 14511 85285 36009 95892 36962 67835 63314 50162 07483 51453 11649 86348 76431 81594 95848 36738 25014 15460 96283 01898 61414 83525 04231 13604 75339 11730 85423 60698 49174 12074 98551 37895 93547 24769 09404 76548 05393 96770 97366 39941 21225 93629 19574 71565 33413 56087 40875 13351

90474 41469 16812 81542 81652 45554 27931 93994 22375 00953 28599 64109 09497 76235 41383 31555 12639 00619 22909 29563 25254 16210 89717 65997 82667 74624 36348 44018 64732 93589 28785 02760 24359 99410 77319 73408 58993 61098 04393 48245 84725 86576 86944 93296 10081 82454 76810 52975 10324 15457

41059 66456 47679 66810 15941 84602 14493 65515 19251 41642 67434 41045 82830 47617 36932 46728 71183 36345 41404 81110 72766 68816 37643 19959 57550 49620 98480 25640 67257 18671 92079 46784 66125 94932 64451 29275 57669 66658 30818 58353 29187 40350 62533 73603 34075 16451 42885 03448 37390 96328

74220 17612 65522 80607 19184 64164 66962 82310 18163 63495 03786 02407 06098 92917 40434 60602 82175 04470 78754 90775 75085 55558 15520 27038 25471 76107 90832 10819 56797 33751 09161 33015 19155 11715 00551 24909 31894 37774 37953 78837 75707 48992 64998 87080 39333 00767 45637 12538 67439 94914

21333 48660 31288 00086 79889 75532 28704 62844 92337 99695 65626 50061 42539 14812 48895 11196 34335 60492 70650 51108 84380 07389 87891 76255 89604 41372 10837 66992 93183 56920 46479 32072 80083 63868 70930 89654 05359 47196 12452 38234 59847 97197 55147 76639 76971 55928 36441 95141 42333 67483

31416 11231 27904 57383 31852 69137 96667 14315 01007 31929 82066 83436 67914 21465 99605 83114 97885 74440 99622 87912 01850 42782 39202 18582 46214 99228 79541 78298 75404 63648 32315 89276 89582 87138 16165 15984 21466 63830 30475 74729 59338 42703 55198 80380 67067 97155 34160 85019 03527 78140

58089 27632 50987 91373 07736 20436 96130 73483 85332 24384 61705 57285 30392 23660 75841 21931 04295 00875 09114 32101 18914 98982 60199 99275 41967 35208 30357 76772 92656 62318 11965 94089 34803 48941 69709 16784 44642 89761 66864 62803 85251 48111 80936 81781 93248 67877 16498 31924 51315 79921

66121 96986 84844 93873 46352 92183 51152 85878 30490 15974 53972 96642 24199 58080 35450 03482 66953 49251 63719 57615 14509 16594 78883 43222 23093 58645 60257 89250 63266 90858 37700 07688 65533 72126 23611 93993 01848 03910 38552 17472 85466 59392 72722 15473 73295 49759 56157 60477 83284 56367

Source: Daniel WW (1974) Biostatistics: a foundation for analysis in the health sciences. John Wiley & Sons, New York, p 417.

274 Appendix Tables

TableA.2. Areas in one tail (~ + z or ;:;a - z) of the standard normal distribution

z 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

0.0 0.500 0.496 0.492 0.488 0.484 0.480 0.476 0.472 0.468 0.464 0.1 0.460 0.456 0.452 0.448 0.444 0.440 0.436 0.433 0.429 0.425 0.2 0.421 0.417 0.413 0.409 0.405 0.401 0.397 0.394 0.390 0.386 0.3 0.382 0.378 0.374 0.371 0.367 0.363 0.359 0.356 0.352 0.348 0.4 0.345 0.341 0.337 0.334 0.330 0.326 0.323 0.319 0.316 0.312

0.5 0.309 0.305 0.302 0.298 0.295 0.291 0.288 0.284 0.281 0.278 0.6 0.274 0.271 0.268 0.264 0.261 0.258 0.255 0.251 0.248 0.245 0.7 0.242 0.239 0.236 0.233 0.230 0.227 0.224 0.221 0.218 0.215 0.8 0.212 0.209 0.206 0.203 0.200 0.198 0.195 0.192 0.189 0.187 0.9 0.184 0.181 0.179 0.176 0.174 0.171 0.169 0.166 0.164 0.161

1.0 0.159 0.156 0.154 0.152 0.149 0.147 0.145 0.142 0.140 0.138 1.1 0.136 0.133 0.131 0.129 0.127 0.125 0.123 0.121 0.119 0.117 1.2 0.115 0.113 0.111 0.109 0.107 0.106 0.104 0.102 0.100 0.099 1.3 0.097 0.095 0.093 0.092 0.090 0.089 0.087 0.085 0.084 0.082 1.4 0.081 0.079 0.078 0.076 0.075 0.074 0.072 0.071 0.069 0.068

1.5 0.067 0.066 0.064 0.063 0.062 0.061 0.059 0.058 0.057 0.056 1.6 0.055 0.054 0.053 0.052 0.051 0.049 0.048 0.048 0.046 0.046 1.7 0.045 0.044 0.043 0.042 0.041 0.040 0.039 0.038 0.038 0.037 1.8 0.036 0.035 0.034 0.034 0.033 0.032 0.031 0.031 0.030 0.029 1.9 0.029 0.028 0.027 0.027 0.026 0.026 0.025 0.024 0.024 0.023

2.0 0.023 0.022 0.022 0.021 0.021 0.020 0.020 0.019 0.019 0.D18 2.1 0.018 0.017 0.017 0.017 0.016 0.016 0.D15 0.015 0.D15 0.014 2.2 0.014 0.014 0.013 0.013 0.013 0.012 0.012 0.012 0.011 0.011 2.3 0.011 0.010 0.010 0.010 0.010 0.009 0.009 0.009 0.009 0.008 2.4 0.008 0.008 0.008 0.008 0.007 0.007 0.007 0.007 0.007 0.006

2.5 0.006 0.006 0.006 0.006 0.006 0.005 0.005 0.005 0.005 0.005 2.6 0.005 0.005 0.004 0.004 0.004 0.004 0.004 0.004 0.004 0.004 2.7 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 2.8 0.003 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 2.9 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.001 0.001 0.001

3.0 0.001

Source: Colton T (1974) Statistics in medicine. Little, Brown, Boston, p 345.

Appendix Tables 275

TableA.3. Areas in two tails (;;:; + z plus;:;; - z) of the standard normal distribution

z 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

0.0 1.000 0.992 0.984 0.976 0.968 0.960 0.952 0.944 0.936 0.928 0.1 0.920 0.912 0.904 0.897 0.889 0.881 0.873 0.865 0.857 0.849 0.2 0.841 0.834 0.826 0.818 0.810 0.803 0.795 0.787 0.779 0.772 0.3 0.764 0.757 0.749 0.741 0.734 0.726 0.719 0.711 0.704 0.697 0.4 0.689 0.682 0.674 0.667 0.660 0.653 0.646 0.638 0.631 0.624

0.5 0.617 0.610 0.603 0.596 0.589 0.582 0.575 0.569 0.562 0.555 0.6 0.549 0.542 0.535 0.529 0.522 0.516 0.509 0.503 0.497 0.490 0.7 0.484 0.478 0.472 0.465 0.459 0.453 0.447 0.441 0.435 0.430 0.8 0.424 0.418 0.412 0.407 0.401 0.395 0.390 0.384 0.379 0.373 0.9 0.368 0.363 0.358 0.352 0.347 0.342 0.337 0.332 0.327 0.322

1.0 0.317 0.312 0.308 0.303 0.298 0.294 0.289 0.285 0.280 0.276 1.1 0.271 0.267 0.263 0.258 0.254 0.250 0.246 0.242 0.238 0.234 1.2 0.230 0.226 0.222 0.219 0.215 0.211 0.208 0.204 0.201 0.197 1.3 0.194 0.190 0.187 0.184 0.180 0.177 0.174 0.171 0.168 0.165 1.4 0.162 0.159 0.156 0.153 0.150 0.147 0.144 0.142 0.139 0.136

1.5 0.134 0.131 0.129 0.126 0.124 0.121 0.119 0.116 0.114 0.112 1.6 0.110 0.107 0.105 0.103 0.101 0.099 0.097 0.095 0.093 0.091 1.7 0.089 0.087 0.085 0.084 0.082 0.080 0.078 0.077 0.075 0.073 1.8 0.072 0.070 0.069 0.067 0.066 0.064 0.063 0.061 0.060 0.059 1.9 0.057 0.056 0.055 0.054 0.052 0.051 0.050 0.049 0.048 0.047

2.0 0.046 0.044 0.043 0.042 0.041 0.040 0.039 0.038 0.038 0.037 2.1 0.036 0.035 0.034 0.033 0.032 0.032 0.031 0.030 0.029 0.029 2.2 0.028 0.027 0.026 0.026 0.Q25 0.024 0.024 0.023 0.023 0.022 2.3 0.021 0.021 0.020 0.020 0.019 0.019 0.018 0.018 0.017 0.017 2.4 0.016 0.016 0.016 0.015 0.015 0.014 0.014 0.014 0.013 0.013

2.5 0.012 0.012 0.012 0.011 0.011 0.011 0.010 0.010 0.010 0.010 2.6 0.009 0.009 0.009 0.009 0.008 0.008 0.008 0.008 0.007 0.007 2.7 0.007 0.007 0.007 0.006 0.006 0.006 0.006 0.006 0.005 0.005 2.8 0.005 0.005 0.005 0.005 0.005 0.004 0.004 0.004 0.004 0.004 2.9 0.004 0.004 0.004 0.003 0.003 0.003 0.003 0.003 0.003 0.003

3.0 0.003

Source: Colton T (1974) Statistics in medicine. Little, Brown, Boston, p 346.

276 Appendix Tables

TableA.4. Critical values of t required for certain P values, according to number of degrees of freedom (df)

P value df One-tailed 0.25 0.1 0.05 0.025 0.01 0.005 0.0025 0.001 0.0005

Two-tailed 0.5 0.2 0.1 0.05 0.02 0.01 0.005 0.002 0.001

1 1.000 3.078 6.314 12.706 31.821 63.657 127.32 318.31 636.62 2 0.816 1.886 2.920 4.303 6.965 9.925 14.089 22.327 31.598 3 0.765 1.638 2.353 3.182 4.541 5.841 7.453 10.214 12.924 4 0.741 1.533 2.132 2.776 3.747 4.604 5.598 7.173 8.610

5 0.727 1.476 2.015 2.571 3.365 4.032 4.773 5.893 6.869 6 0.718 1.440 1.943 2.447 3.143 3.707 4.317 5.208 5.959 7 0.711 1.415 1.895 2.365 2.998 3.499 4.029 4.785 5.408 8 0.706 1.397 1.860 2.306 2.896 3.355 3.833 4.501 5.041 9 0.703 1.383 1.833 2.262 2.821 3.250 3.690 4.297 4.781

10 0.700 1.372 1.812 2.228 2.764 3.169 3.581 4.144 4.587 11 0.697 1.363 1.796 2.201 2.718 3.106 3.497 4.025 4.437 12 0.695 1.356 1.782 2.179 2.681 3.055 3.428 3.930 4.318 13 0.694 1.350 1.771 2.160 2.650 3.012 3.372 3.852 4.221 14 0.692 1.345 1.761 2.145 2.624 2.977 3.326 3.787 4.140

15 0.691 1.341 1.753 2.131 2.602 2.947 3.286 3.733 4.073 16 0.690 1.337 1.746 2.120 2.583 2.921 3.252 3.686 4.015 17 0.689 1.333 1.740 2.110 2.567 2.898 3.222 3.646 3.965 18 0.688 1.330 1.734 2.101 2.552 2.878 3.197 3.610 3.922 19 0.688 1.328 1.729 2.093 2.539 2.861 3.174 3.579 3.883

20 0.687 1.325 1.725 2.086 2.528 2.845 3.153 3.552 3.850 21 0.686 1.323 1.721 2.080 2.518 2.831 3.135 3.527 3.819 22 0.686 1.321 1.717 2.074 2.508 2.819 3.119 3.505 3.792 23 0.685 1.319 1.714 2.069 2.500 2.807 3.104 3.485 3.767 24 0.685 1.318 1.711 2.064 2.492 2.797 3.091 3.467 3.745

25 0.684 1.316 1.708 2.060 2.485 2.787 3.078 3.450 3.725 26 0.684 1.315 1.706 2.056 2.479 2.779 3.067 3.435 3.707 27 0.684 1.314 1.703 2.052 2.473 2.771 3.057 3.421 3.690 28 0.683 1.313 1.701 2.048 2.467 2.763 3.047 3.408 3.674 29 0.683 1.311 1.699 2.045 2.462 2.756 3.038 3.396 3.659

30 0.683 1.310 1.697 2.042 2.457 2.750 3.030 3.385 3.646 40 0.681 1.303 1.684 2.021 2.423 2.704 2.971 3.307 3.551 60 0.679 1.296 1.671 2.000 2.390 2.660 2.915 3.232 3.460

120 0.677 1.289 1.658 1.980 2.358 2.617 2.860 3.160 3.373 00 0.674 1.282 1.645 1.960 2.326 2.576 2.807 3.090 3.291

Source: Pearson ES, Hartley HO (eds) (1976) Biometrika tables for statisticians, voL I. Biometrika Trust, London, p 146.

Appendix Tables 277

Table A.5. Critical values of U for certain P values, according to sample sizes (nl and n2) of two compared groups (for Mann-Whitney U-test) A. P=0.05 (one-tailed) or 0.10 (two-tailed)

n2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

nl 2 0 0 0 0 1 1 1 2 2 2 3 3 3 4 4 4 3 0 0 1 2 2 3 3 4 5 5 6 7 7 8 9 9 10 11 4 1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 17 18 5 3 5 6 8 9 11 12 13 15 16 18 19 20 22 23 25

6 7 8 10 12 14 16 17 19 21 23 25 26 28 30 32 7 11 13 15 17 19 21 24 26 28 30 33 35 37 39 8 15 18 20 23 26 28 31 33 36 39 41 44 47 9 21 24 27 30 33 36 39 42 45 48 51 54

10 27 31 34 37 41 44 48 51 55 58 62

11 34 38 42 46 50 54 57 61 65 69 12 42 47 51 55 60 64 68 72 77 13 51 56 61 65 70 75 80 84 14 61 66 71 77 82 87 92 15 72 77 83 88 94 100 16 83 89 95 101 107 17 96 102 109 115 18 109 116 123 19 123 130 20 138

B. P= 0.025 (one-tailed) or 0.05 (two-tailed)

nz 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

nl 2 0 0 0 0 1 1 1 1 1 2 2 2 3 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 4 0 1 2 3 4 4 5 6 7 8 9 10 11 11 12 13 13 5 2 3 5 6 7 8 9 11 12 13 14 15 17 18 19 20

6 5 6 8 10 11 13 14 16 17 19 21 22 24 25 27 7 8 10 12 14 16 18 20 22 24 26 28 30 32 34 8 13 15 17 19 22 24 26 29 31 34 36 38 41 9 17 20 23 26 28 31 34 37 39 42 45 48

10 23 26 29 33 36 39 42 45 48 52 55

11 30 33 37 40 44 47 51 55 58 62 12 37 41 45 49 53 57 61 65 69 13 45 50 54 59 63 67 72 76 14 55 59 64 67 74 78 83 15 64 70 75 80 85 90 16 75 81 86 92 98 17 87 93 99 105 18 99 106 112 19 113 119 20 127

278 Appendix Tables

Table A.S. (continued) C. P=O.Ol (one-tailed) or 0.02 (two-tailed)

1Iz 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

nl 2 0 0 0 0 0 0 1 3 0 0 1 1 2 2 2 3 3 4 4 4 5 4 0 0 1 2 3 3 4 5 5 6 7 7 8 9 9 10 5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

6 3 4 6 7 8 9 11 12 13 15 16 18 19 20 22 7 6 8 9 11 12 14 16 17 19 21 23 24 26 28 8 10 11 13 15 17 20 22 24 26 28 30 32 34 9 14 16 18 21 23 26 28 31 33 36 38 40

10 19 22 24 27 30 33 36 38 41 44 47

11 25 28 31 34 37 41 44 47 50 53 12 31 35 38 42 46 49 53 56 60 13 39 43 47 51 55 59 63 67 14 47 51 56 60 65 69 73 15 56 61 66 70 75 80 16 66 71 76 82 87 17 77 82 88 93 18 88 94 100 19 101 107 20 114

Source: SmartJV (1963) Elements of medical statistics. Charles C. Thomas, Springfield, MA, pp 125-127.

Appendix Tables 279

Table A.6. Critical values of sums of ranks for certain P values, according to sample size (n) in each of two pair-matched groups (for Wilcoxon signed rank test). Entry before comma represents maxi-mum value for lower sum; entry after comma is minimum value for higher sum

n One-tailed 0.Q25 0.01 0.005 (number Pvalue of pairs) Two-tailed 0.05 0.02 0.01

6 0,21 7 2,26 0,28 8 3,33 1,35 0,36 9 5,40 3,42 1,44

10 8,47 5,50 3,52

11 10,56 7, 59 5,61 12 13,65 9,69 7, 71 13 17,74 12,79 9, 82 14 21,84 15,90 12,93 15 25,95 19,101 15, 105

16 29, 107 23, 113 19, 117 17 34, 119 28, 125 23, 130 18 40, 131 32,139 27, 144 19 46,144 37, 153 32,158 20 52, 158 43, 167 37, 173

21 58, 173 49, 182 42, 189 22 66, 187 55, 198 48,205 23 73,203 62,214 54,222 24 81,219 69,231 61,239 25 89,236 76,249 68,257

Source: Colton T (1974) Statistics in medicine. Little, Brown, Boston, p 350.

280 Appendix Tables

TableA.7. Critical values of "l required for certain P values (two-tailed only), according to num-ber of degrees of freedom (df)

Two-tailed P value df

0.10 0.05 0.01 0.001

2.71 3.84 6.63 10.83 2 4.61 5.99 9.21 13.82 3 6.25 7.81 11.34 16.27 4 7.78 9.49 13.28 18.47 5 9.24 11.07 15.09 20.52

6 10.64 12.59 16.81 22.46 7 12.02 14.07 18.48 24.32 8 13.36 15.51 20.09 26.13 9 14.68 16.92 21.67 27.88

10 15.99 18.31 23.21 29.59

11 17.28 19.68 24.73 31.26 12 18.55 21.03 26.22 32.91 13 19.81 22.36 27.69 34.53 14 21.06 23.68 29.14 36.12 15 22.31 25.00 30.58 37.70

16 23.54 26.30 32.00 39.25 17 24.77 27.59 33.41 40.79 18 25.99 28.87 34.81 42.31 19 27.20 30.14 36.19 43.82 20 28.41 31.41 37.57 45.32

21 29.62 32.67 38.93 46.80 22 30.81 33.92 40.29 48.27 23 32.01 35.17 41.64 49.73 24 33.20 36.42 42.98 51.18 25 34.38 37.65 44.31 52.62

Source: Colton T (1974) Statistics in medicine. Little, Brown, Boston, p 348.

Appendix Tables 281

Table A.S. Critical values of Spearman rank correlation coefficient (r,) for certain P values, accord­ing to sample size (n)

n One-tailed 0.025 0.005 (number Pvalue

of pairs) Two-tailed 0.05 0.01

6 0.886 1.000 7 0.786 0.929 8 0.738 0.881 9 0.683 0.833

10 0.648 0.794

11 0.623 0.818 12 0.591 0.780 13 0.566 0.745 14 0.545 0.716 15 0.525 0.689

16 0.507 0.666 17 0.490 0.645 18 0.476 0.625 19 0.462 0.608 20 0.450 0.591

21 0.438 0.576 22 0.428 0.562 23 0.418 0.549 24 0.409 0.537 25 0.400 0.526

26 0.392 0.515 27 0.385 0.505 28 0.377 0.496 29 0.370 0.487 30 0.364 0.478

Sources: Colton T (1974) Statistics in medicine. Little, Brown, Boston, p 353. Snedecor GW, Cochran WG (1980) Statistical methods, 7th edn. Iowa State University Press, Ames, p 478.

Subject Index

Alternative hypothesis 142-144 Analysis of covariance 164 Analysis of variance 162-163 Analytic studies 37

Baseline state 59 Bayes' theorem

applied to causality assessment 267-268 applied to diagnostic tests 213-216 likelihood ratio 144,215-216,267 posterior odds 215-216, 267 posterior probability 144, 214-215 prior odds 215-216,267 prior probability 144,214

Bias analytic bias 16, 47-57, 261-262 Berkson's bias 51, 106 confounding bias 32, 49, 53-56, 70-74, 91,

107-110, 163-164, 176-178, 195-196, 252-253,261-262

detection bias (see information bias) due to nonresponse 18-19 in individual measurements 12-16 information bias 16, 49, 52-53,69-70, 85,

107, 115,261 lead-time bias 217-218 reverse causality bias 40, 49, 56-57, 115,

117, 262 sample distortion bias 49-52,70,91,

106-107, 115,261 selection bias (see sample distortion bias)

Binomial distribution 134-135 Blinding 17, 18, 19,53,70,71,84-85, 107,

115

Case-control studies advantages and disadvantages 110-111 analysis of results 96-106 ascertainment of exposure 95-96 bias assessment and control 106-11 ° definition 40, 42-44 matched 108 odds ratio 98-105

selection of cases 94 selection of controls 94-95

Causality Can it? 260-264 causal networks 259 causal paths 54, 258-259 definition 254-256 Did it? 260, 265-268 multifactorial 257 necessary cause 256-257 sufficient cause 256-257 weighing the evidence for 261-264 Will it? 260, 264-265

Central Limit Theorem 146-147, 159 Chi-square (X2) test

continuity correction 171-172, 174 for comparing three or more proportions

183-185 for comparing two proportions 167-1.78 for linear trend 184-185 for rx ccontingency tables 185-186 for testing a single proportion 181-182 for testing goodness of fit 182 Mantel-Haenszel 176-177 McNemar 174-175

Clinical trials advantages and disadvantages 91 assignment of treatment 80-84 crossover design 84 definition 6, 45, 58, 78 double-blinding 85 ethics 88-91 informed consent 89 parallel design 84 placebo treatment 79 randomization 55, 80-84 sequential design 90 treatment compliance 79

Coefficient of variation 128 Cohort analysis 116 Cohort effect 116 Cohort studies

advantages and disadvantages 76 analysis of results 63-69 attributable risk 65- 67

284

Cohort studies baseline state 59 bias assessment and control 69-74 definition 40, 42-44 exposure 59-60 follow-up 61-62 matched 70-72 outcome 62 relative risk 65-69 sample selection 58-59

Conditional probability 144,213-216, 226-228, 267

Confidence interval for correlation coefficient 194-195 for difference in means 154, 156 for difference in proportions 179 for odds ratio 175-176 for relative risk 175-176 for single mean 148-149 for single proportion 183 for survival rate 247-248 in statistical inference 122, 123

Confounding (see Bias) Correlation coefficient 189-190, 192-194,

196-197 Cost-benefit analysis 7, 233-234 Cost-effectiveness analysis 7,234-235 Critical ratio 147 Cross-sectional studies

advantages and disadvantages 116-117 analysis of results 114-115 bias assessment and control 115 definition 40, 42-45 exposure 114 outcome 113-114 "pseudo-cohort" studies 115-116 sample selection in 113

Data sources 17-23 Decision analysis

decision trees 222-225 probabilities 225-228 sensitivity analysis 230-232 threshold analysis 232-233 utilities 228-231 vs other decision strategies 220-222

Degrees of freedom 127, 147-148, 170 Descriptive statistics 122, 124-136 Diagnostic tests

Bayes' theorem applied to 213-216 case-finding 217 criteria for "normal" and "abnormal" results

201-205 lead-time bias 217-218 predictive value 211-216 reproducibility 205

screening 217-218 sensitivity 205-210 specificity 205-210

Subject Index

spectrum and bias in interpretation of 208-210

validity 205 zero-time shift 217-218

Directionality (in research design) 39-40 Discriminant function analysis 177 Dose-response effect 60, 104-105, 184-185,

263

Ecological fallacy 23 Effect modification 74-76, 110, 164, 177-178,

196,256-257 Effectiveness 86-87 Efficacy 86-87 Epidemiology

classicial 4 clinical 4-8 definition 3 history 8-10

Etiologic fraction 67, 105-106, 266 Experimental studies, definition 38 Exposure, definition 38-39, 59, 254

F-test 162 Factorial design 163 Fisher exact test 172-174 Frequency distributions 124-125, 129-135

Gaussian distribution (see Normal distribution) Groups

dynamic 29-30, 65 fixed 27,65

Hawthorne effect 87-88 Hazard 243, 246, 252-253 Histogram 124-125 Hypergeometric distribution 172 Hypothesis testing 137-145

Incidence density rate 30, 65 density ratio 68, 102 rate 27-31

Informed consent 89 Interaction (see Effect modification)

Latent period 30,40,61,68,76, 80,95, 114, 115,239-240

Subject Index

Life-table (survival) analysis actuarial method 240-244 confidence intervals in 247-248 Kaplan-Meier (product-limit) method

245-247 log-rank rest for comparing two groups

251-252 proportional hazards model 252-253 survival curve 244, 246, 248-253 vs other methods of analysis 237-240 z-test for comparing two groups 248-251

Likelihood ratio (see Bayes' theorem) Linear correlation 187-190, 192-193 Linear regression 191-193, 195-196

Mann-Whitney U-test 160-161 Mantel-Haenszel procedure

chi-square (x2) test 176-177 odds ratio 108-110 relative risk 72-74

Matching 55-56,70-71, 108, 115, 154-156, 174-175, 176

McNemar X2 test 174-175 Mean 126, 146 Measurement

bias 12-16 detail 14 "hard" vs "soft" 15 method variability 12 observer variability 12 random (chance) error. 12-13,15-16 regression toward the mean 13 reproducibility 12-16 validity 13

Median 126 Mode 126 Multiple linear regression 195-196 Multiple logistic regression 110, 177

Nonparametric tests definition 159 Mann-Whitney U-test 160-161 rank (Spearman) correlation 196-197 sign test 162 Wilcoxon signed rank test 161-162

Normal distribution (also see z-Distribution) 129-130,201-204

Null hypothesis 137-144

Observational studies, definition 38 Odds 97-98, 144 Odds ratio 97-105, 114-115, 175-177, 181 Outcome, definition 38-39, 62, 254

Pvalues 122-123, 138-143 Parameter 122, 129 Parametric estimation 122 Percentile range 127 Pie chart 133-134 Poisson distribution 135 Pooled variance 152-153 Population 121-122 Posterior odds (see Bayes' theorem) Posterior probability (see Bayes' theorem) Predictive value (see Diagnostic tests) Prevalence

rate 27-29, 31-32 rate ratio 114

Prior odds (see Bayes' theorem) Prior probability (see Bayes' theorem) Proportion 133, 166 "Prospective" studies 45

Random sampling 41-42 Randomization (see Clinical trials) Rank (Spearman) correlation 196-197 Rates

adjustment of 32-35 attack 30-31 case fatality 30 crude 32 direct standardization of 33-34 incidence 27-31 incidence density 30, 65 indirect standardization of 34-35 prevalence 27-29,31-32

285

Receiver operating characteristics (ROC) curve (see Diagnostic tests)

Regression coefficient 191-194 Relative risk (see Risk) Reproducibility

of diagnostic tests 205 of exposure-outcome associations 37, 47 of individual measurements 12-16

Research hypothesis 137, 142, 143 Restriction 55-56 "Retrospective" studies 45 Risk

attributable risk 65-69,71-72 definition 65 ratio 65 relative risk 65-69,71-72,98-104,

175-176, 181,250-253

Sample distortion 49-52 sampling distribution 146-147, 151 sampling variation 47, 121-122 selection 39-42, 48-49

286

Sample size definition 126 for comparing two means 157-159 for comparing two proportions 179-181

Scatter diagram 187-188 Sensitivity (see Diagnostic tests) Sign test 162 Simpson's paradox 74 Skewness 126-127, 159 Spearman's rho 196-197 Specificity (see Diagnostic tests) Standard deviation 127-130 Standard error of the mean 128, 146 Standard normal distribution (see z-Distribu-

tion) Standardization (see Rates) Statistical inference 122, 137-145 Statistical power 142-143, 157, 180 Statistical significance 138-141, 157-159,263 Stratification 32-35,56,72-75,83,108-110,

164, 176-177,252 Survival analysis (see Life-table analysis)

t-Distribution 147-148 t-Test

for correlation coefficient 194 one-sample t-test 149-150 paired t-test 154-156 two-sample t-test 150-154

Subject Index

Target population 37-38,47-52, 121 Timing (in research design) 39,42,44 Treatment (see Exposure) Two-by-two (fourfold) tables

matched 70-72, 108, 166-174 stratified 72-75,108-110, 176-178 unmatched 64-66,97-104, 174-175

Type I error 139-142, 157-159, 180-181 Type II error 141-143, 157-159, 179-181

Validity (also see Measurement) external validity 48-49 internal validity 48-49 of diagnostic tests 205-206 of exposure-outcome associations 37, 47 of individual measurements 13-16

Variables definition 11 dependent 189-190 independent 189-190 types of 11,121

Variance 127, 129, 151 Vital statistics 21-22,31

Wilcoxon signed rank test 161-162

z-Distribution 130-133 z-Test 150, 157,248-251 Zero time 61,217-218,240,242