Two-Sample T-Test Examples

Statistics · Axiom Academy

EXAMPLE Two-Sample T-Test Examples Comparing means between two independent groups Study: Comparing Two Teaching Methods A school tests two teaching methods for mathematics. Students are randomly assigned to either Method A (traditional) or Method B (interactive). After 8 weeks, all students take the same test. Test at α = 0.05. Assume equal variances. Study: Drug Effectiveness Trial Researchers test a new drug for reducing blood pressure. Patients are randomly assigned to treatment or control (placebo). Blood pressure reduction (mmHg) is measured after 4 weeks. Test at α = 0.01. Use Welch's t-test (unequal variances). Study: Comparing Bank Branch Wait Times A bank wants to compare customer wait times at two branches. Random samples of customer wait times (in minutes) are collected during peak hours. Excellent work! You've completed three two-sample t-test examples. Here's what we learned: Pooled t-test (equal variances): Used when population variances are assumed equal. Combines sample variances to estimate the common variance, resulting in more degrees of freedom and potentially more power. Welch's t-test (unequal variances): Used when variances differ between groups. Does not pool variances and uses the Welch-Satterthwaite equation for degrees of freedom, providing more accurate results when variances are unequal.

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