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Understanding Hypothesis Testing

What is Hypothesis Testing?

Hypothesis testing is a statistical method used to make decisions about populations based on sample data. Key concepts include:

  • Null hypothesis (H₀) - Initial assumption
  • Alternative hypothesis (H₁) - Competing claim
  • Test statistic - Standardized sample measure
  • P-value - Probability of more extreme results
  • Significance level - Decision threshold
  • Critical values - Decision boundaries
  • Type I error - False rejection of H₀
  • Type II error - False acceptance of H₀

Key Formulas

Z-Test Statistic:

z = (x̄ - μ₀)/(σ/√n)

T-Test Statistic:

t = (x̄ - μ₀)/(s/√n)

Proportion Test Statistic:

z = (p̂ - p₀)/√(p₀(1-p₀)/n)

Critical Values:

Two-tailed: ±z_(α/2) or ±t_(α/2,n-1)

One-tailed: z_α or t_(α,n-1)

Test Types

Z-Test

  • Known population standard deviation
  • Large sample size (n ≥ 30)
  • Normal distribution assumption
  • Uses standard normal distribution

T-Test

  • Unknown population standard deviation
  • Small sample size (n < 30)
  • Normal distribution assumption
  • Uses t-distribution

Proportion Test

  • Binary outcomes
  • Large sample size (np₀ ≥ 10)
  • Normal approximation
  • Uses standard normal distribution

Applications

Scientific Research

  • Clinical trials
  • Drug testing
  • Treatment effects
  • Experimental validation

Business

  • Quality control
  • Market research
  • A/B testing
  • Process improvement

Social Sciences

  • Survey analysis
  • Behavioral studies
  • Educational research
  • Policy evaluation