Exploratory Data Analysis
1.3. EDA Techniques
1.3.6. Probability Distributions
188.8.131.52. Tables for Probability Distributions
|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.
Given a specified value for α :
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