Perform statistical hypothesis tests for normal population parameters. Calculate test statistics, critical values, P-values, and make statistical decisions with step-by-step explanations.
T-Test: Use when population variance σ² is unknown
Test Statistic:
Critical Values: Use t-distribution with n-1 degrees of freedom
Understanding the statistical principles behind hypothesis testing
Type I Error (α): Rejecting H₀ when it's true (false positive)
Significance Level: Maximum acceptable Type I error rate
Type II Error (β): Failing to reject H₀ when it's false (false negative)
Power: 1 - β, probability of correctly rejecting false H₀
Definition: Probability of observing test statistic as extreme or more extreme, assuming H₀ is true
Decision Rule:
• P-value < α → Reject H₀
• P-value ≥ α → Fail to reject H₀
Note: P-value measures strength of evidence against H₀, not probability that H₀ is true
U-Test (Z-Test): Normal population, σ² known
T-Test: Normal population, σ² unknown
Chi-square Test: Test population variance
Assumptions: Random sampling, independence, normality (for small samples)
Large samples: Central Limit Theorem allows approximate normality
❌ Don't say: "Accept H₀" → Say: "Fail to reject H₀"
❌ Don't confuse: Statistical vs practical significance
❌ Don't interpret: P-value as P(H₀ is true)
✅ Do check: Assumptions before testing
✅ Do consider: Effect size and context
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Theory & Concepts