Section C.2 \(t\)-Probability Table
A \(t\)-probability table may be used to find tail areas of a \(t\)-distribution using a T-score, or vice-versa. Such a table lists T-scores and the corresponding percentiles. Each row in the \(t\)-table represents a \(t\)-distribution with different degrees of freedom. The columns correspond to tail probabilities.
| one tail | 0.100 | 0.050 | 0.025 | 0.010 | 0.005 |
|---|---|---|---|---|---|
| two tails | 0.200 | 0.100 | 0.050 | 0.020 | 0.010 |
| df 1 | 3.08 | 6.31 | 12.71 | 31.82 | 63.66 |
| 2 | 1.89 | 2.92 | 4.30 | 6.96 | 9.92 |
| 3 | 1.64 | 2.35 | 3.18 | 4.54 | 5.84 |
| 4 | 1.53 | 2.13 | 2.78 | 3.75 | 4.60 |
| 5 | 1.48 | 2.02 | 2.57 | 3.36 | 4.03 |
| 6 | 1.44 | 1.94 | 2.45 | 3.14 | 3.71 |
| 7 | 1.41 | 1.89 | 2.36 | 3.00 | 3.50 |
| 8 | 1.40 | 1.86 | 2.31 | 2.90 | 3.36 |
| 9 | 1.38 | 1.83 | 2.26 | 2.82 | 3.25 |
| 10 | 1.37 | 1.81 | 2.23 | 2.76 | 3.17 |
| 15 | 1.34 | 1.75 | 2.13 | 2.60 | 2.95 |
| 20 | 1.33 | 1.72 | 2.09 | 2.53 | 2.85 |
| 25 | 1.32 | 1.71 | 2.06 | 2.49 | 2.79 |
| 30 | 1.31 | 1.70 | 2.04 | 2.46 | 2.75 |
| 40 | 1.30 | 1.68 | 2.02 | 2.42 | 2.70 |
| 50 | 1.30 | 1.68 | 2.01 | 2.40 | 2.68 |
| 60 | 1.30 | 1.67 | 2.00 | 2.39 | 2.66 |
| 80 | 1.29 | 1.66 | 1.99 | 2.37 | 2.64 |
| 100 | 1.29 | 1.66 | 1.98 | 2.36 | 2.63 |
| 200 | 1.29 | 1.65 | 1.97 | 2.35 | 2.60 |
| 500 | 1.28 | 1.65 | 1.96 | 2.33 | 2.59 |
| \(\infty\) | 1.28 | 1.64 | 1.96 | 2.33 | 2.58 |
