Determining Sample Size (Test for a Single Population Mean)

When conducting a one-sample t-test, this tool calculates the required sample size given the effect size (Δ = (μ - μ₀)/σ—how many times the standard deviation is the difference in means?) and the significance level.　Null hypothesis: μ = μ₀; for the alternative hypothesis, you can choose from three options: μ ≠ μ₀, μ > μ₀, or μ < μ₀.