SIX SIGMA Reference Tables
Percentage Points of the t Distribution
n
0.4
0.25
0.1
0.05
0.025
0.01
0.005
0.0025
0.001
0.0005
1
0.325
1.000
3.078
6.314
12.706
31.821
63.656
127.321
318.289
636.578
2
0.289
0.816
1.886
2.920
4.303
6.965
9.925
14.089
22.328
31.600
3
0.277
0.765
1.638
2.353
3.182
4.541
5.841
7.453
10.214
12.924
4
0.271
0.741
1.533
2.132
2.776
3.747
4.604
5.598
7.173
8.610
5
0.267
0.727
1.476
2.015
2.571
3.365
4.032
4.773
5.894
6.869
6
0.265
0.718
1.440
1.943
2.447
3.143
3.707
4.317
5.208
5.959
7
0.263
0.711
1.415
1.895
2.365
2.998
3.499
4.029
4.785
5.408
8
0.262
0.706
1.397
1.860
2.306
2.896
3.355
3.833
4.501
5.041
9
0.261
0.703
1.383
1.833
2.262
2.821
3.250
3.690
4.297
4.781
10
0.260
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
0.259
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
0.258
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
0.257
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
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
0.256
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
3.768
24
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
3.450
3.725
26
1.315
1.706
2.056
2.479
2.779
3.067
3.435
27
1.314
1.703
2.052
2.473
2.771
3.057
3.421
3.689
28
0.683
1.313
1.701
2.048
2.467
2.763
3.047
3.408
3.674
29
1.311
1.699
2.045
2.462
2.756
3.038
3.396
3.660
30
1.310
1.697
2.042
2.457
2.750
3.030
3.385
40
0.255
0.681
1.303
1.684
2.021
2.423
2.704
2.971
3.307
3.551
60
0.254
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
0.253
0.674
1.282
1.645
1.960
2.326
2.576
3.090
3.291