How it's calculated
t = (x̄ − μ₀) ÷ (s ÷ √n), df = n − 1
x̄ = sample mean, μ₀ = hypothesized mean, s = sample standard deviation, n = sample size, df = degrees of freedom. s ÷ √n is the standard error.
Common questions
What does the t-statistic tell me?
It measures how far your sample mean sits from the hypothesized mean in units of standard error. Larger absolute values point to a bigger difference.
What are degrees of freedom here?
For a one-sample test, degrees of freedom equal the sample size minus one. They set the shape of the t distribution used for the p-value.