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1. Exploratory Data Analysis
1.3. EDA Techniques
1.3.6. Probability Distributions
1.3.6.7. Tables for Probability Distributions

1.3.6.7.2.

Critical Values of the Student's t Distribution

How to Use This Table This table contains critical values of the Student's t distribution computed using the cumulative distribution function. The t distribution is symmetric so that

t1-α,ν = -tα,ν.

The t table can be used for both one-sided (lower and upper) and two-sided tests using the appropriate value of α.

The significance level, α, is demonstrated in the graph below, which displays a t distribution with 10 degrees of freedom. The most commonly used significance level is α = 0.05. For a two-sided test, we compute 1 - α/2, or 1 - 0.05/2 = 0.975 when α = 0.05. If the absolute value of the test statistic is greater than the critical value (0.975), then we reject the null hypothesis. Due to the symmetry of the t distribution, we only tabulate the positive critical values in the table below.

two-sided test for alpha = 0.05

Given a specified value for α :

  1. For a two-sided test, find the column corresponding to 1-α/2 and reject the null hypothesis if the absolute value of the test statistic is greater than the value of t1-α/2,ν in the table below.
  2. For an upper, one-sided test, find the column corresponding to 1-α and reject the null hypothesis if the test statistic is greater than the table value.
  3. For a lower, one-sided test, find the column corresponding to 1-α and reject the null hypothesis if the test statistic is less than the negative of the table value.

Critical values of Student's t distribution with ν degrees of freedom

     Probability less than the critical value (t1-α,ν)

  ν         0.90    0.95   0.975    0.99   0.995   0.999

1. 3.078 6.314 12.706 31.821 63.657 318.313 2. 1.886 2.920 4.303 6.965 9.925 22.327 3. 1.638 2.353 3.182 4.541 5.841 10.215 4. 1.533 2.132 2.776 3.747 4.604 7.173 5. 1.476 2.015 2.571 3.365 4.032 5.893 6. 1.440 1.943 2.447 3.143 3.707 5.208 7. 1.415 1.895 2.365 2.998 3.499 4.782 8. 1.397 1.860 2.306 2.896 3.355 4.499 9. 1.383 1.833 2.262 2.821 3.250 4.296 10. 1.372 1.812 2.228 2.764 3.169 4.143 11. 1.363 1.796 2.201 2.718 3.106 4.024 12. 1.356 1.782 2.179 2.681 3.055 3.929 13. 1.350 1.771 2.160 2.650 3.012 3.852 14. 1.345 1.761 2.145 2.624 2.977 3.787 15. 1.341 1.753 2.131 2.602 2.947 3.733 16. 1.337 1.746 2.120 2.583 2.921 3.686 17. 1.333 1.740 2.110 2.567 2.898 3.646 18. 1.330 1.734 2.101 2.552 2.878 3.610 19. 1.328 1.729 2.093 2.539 2.861 3.579 20. 1.325 1.725 2.086 2.528 2.845 3.552 21. 1.323 1.721 2.080 2.518 2.831 3.527 22. 1.321 1.717 2.074 2.508 2.819 3.505 23. 1.319 1.714 2.069 2.500 2.807 3.485 24. 1.318 1.711 2.064 2.492 2.797 3.467 25. 1.316 1.708 2.060 2.485 2.787 3.450 26. 1.315 1.706 2.056 2.479 2.779 3.435 27. 1.314 1.703 2.052 2.473 2.771 3.421 28. 1.313 1.701 2.048 2.467 2.763 3.408 29. 1.311 1.699 2.045 2.462 2.756 3.396 30. 1.310 1.697 2.042 2.457 2.750 3.385 31. 1.309 1.696 2.040 2.453 2.744 3.375 32. 1.309 1.694 2.037 2.449 2.738 3.365 33. 1.308 1.692 2.035 2.445 2.733 3.356 34. 1.307 1.691 2.032 2.441 2.728 3.348 35. 1.306 1.690 2.030 2.438 2.724 3.340 36. 1.306 1.688 2.028 2.434 2.719 3.333 37. 1.305 1.687 2.026 2.431 2.715 3.326 38. 1.304 1.686 2.024 2.429 2.712 3.319 39. 1.304 1.685 2.023 2.426 2.708 3.313 40. 1.303 1.684 2.021 2.423 2.704 3.307 41. 1.303 1.683 2.020 2.421 2.701 3.301 42. 1.302 1.682 2.018 2.418 2.698 3.296 43. 1.302 1.681 2.017 2.416 2.695 3.291 44. 1.301 1.680 2.015 2.414 2.692 3.286 45. 1.301 1.679 2.014 2.412 2.690 3.281 46. 1.300 1.679 2.013 2.410 2.687 3.277 47. 1.300 1.678 2.012 2.408 2.685 3.273 48. 1.299 1.677 2.011 2.407 2.682 3.269 49. 1.299 1.677 2.010 2.405 2.680 3.265 50. 1.299 1.676 2.009 2.403 2.678 3.261 51. 1.298 1.675 2.008 2.402 2.676 3.258 52. 1.298 1.675 2.007 2.400 2.674 3.255 53. 1.298 1.674 2.006 2.399 2.672 3.251 54. 1.297 1.674 2.005 2.397 2.670 3.248 55. 1.297 1.673 2.004 2.396 2.668 3.245 56. 1.297 1.673 2.003 2.395 2.667 3.242 57. 1.297 1.672 2.002 2.394 2.665 3.239 58. 1.296 1.672 2.002 2.392 2.663 3.237 59. 1.296 1.671 2.001 2.391 2.662 3.234 60. 1.296 1.671 2.000 2.390 2.660 3.232 61. 1.296 1.670 2.000 2.389 2.659 3.229 62. 1.295 1.670 1.999 2.388 2.657 3.227 63. 1.295 1.669 1.998 2.387 2.656 3.225 64. 1.295 1.669 1.998 2.386 2.655 3.223 65. 1.295 1.669 1.997 2.385 2.654 3.220 66. 1.295 1.668 1.997 2.384 2.652 3.218 67. 1.294 1.668 1.996 2.383 2.651 3.216 68. 1.294 1.668 1.995 2.382 2.650 3.214 69. 1.294 1.667 1.995 2.382 2.649 3.213 70. 1.294 1.667 1.994 2.381 2.648 3.211 71. 1.294 1.667 1.994 2.380 2.647 3.209 72. 1.293 1.666 1.993 2.379 2.646 3.207 73. 1.293 1.666 1.993 2.379 2.645 3.206 74. 1.293 1.666 1.993 2.378 2.644 3.204 75. 1.293 1.665 1.992 2.377 2.643 3.202 76. 1.293 1.665 1.992 2.376 2.642 3.201 77. 1.293 1.665 1.991 2.376 2.641 3.199 78. 1.292 1.665 1.991 2.375 2.640 3.198 79. 1.292 1.664 1.990 2.374 2.640 3.197 80. 1.292 1.664 1.990 2.374 2.639 3.195 81. 1.292 1.664 1.990 2.373 2.638 3.194 82. 1.292 1.664 1.989 2.373 2.637 3.193 83. 1.292 1.663 1.989 2.372 2.636 3.191 84. 1.292 1.663 1.989 2.372 2.636 3.190 85. 1.292 1.663 1.988 2.371 2.635 3.189 86. 1.291 1.663 1.988 2.370 2.634 3.188 87. 1.291 1.663 1.988 2.370 2.634 3.187 88. 1.291 1.662 1.987 2.369 2.633 3.185 89. 1.291 1.662 1.987 2.369 2.632 3.184 90. 1.291 1.662 1.987 2.368 2.632 3.183 91. 1.291 1.662 1.986 2.368 2.631 3.182 92. 1.291 1.662 1.986 2.368 2.630 3.181 93. 1.291 1.661 1.986 2.367 2.630 3.180 94. 1.291 1.661 1.986 2.367 2.629 3.179 95. 1.291 1.661 1.985 2.366 2.629 3.178 96. 1.290 1.661 1.985 2.366 2.628 3.177 97. 1.290 1.661 1.985 2.365 2.627 3.176 98. 1.290 1.661 1.984 2.365 2.627 3.175 99. 1.290 1.660 1.984 2.365 2.626 3.175 100. 1.290 1.660 1.984 2.364 2.626 3.174 infinity 1.282 1.645 1.960 2.326 2.576 3.090
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