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4.5.1 Central Limit Theorem

Overview

  • Purpose: The Central Limit Theorem (CLT) explains how the sampling distribution of the sample mean (x̄) becomes approximately normal regardless of the population's original distribution, given a sufficiently large sample size.

Key Concepts

  • Sampling Distribution of x̄:
  • Even if the population distribution is not normal, the distribution of the sample mean x̄ will approximate a normal distribution as the sample size increases.
  • This approximation becomes effective when the sample size (n) is 30 or more.

Practical Implications

  • Normal Approximation:
  • For any population with mean (μ) and standard deviation (σ), the mean of x̄ is μ and the standard deviation (σ_x̄) of x̄ is σ/√n, known as the standard error.
  • As n increases, σ_x̄ decreases, which means the sampling distribution of x̄ becomes more concentrated around μ.

Central Limit Theorem Application

  • Statistical Inference:
  • CLT allows for making probabilistic statements about how close x̄ is to μ using the normal distribution model.
  • This is crucial for hypothesis testing and constructing confidence intervals in practical business scenarios.

Example Application

  • Visual Illustration:
  • Various population shapes (Normal, Uniform, Exponential, Arbitrary) show that as n increases to 30 or more, the sampling distribution of x̄ closely resembles a normal distribution.

Conclusion

  • Significance in Business Statistics:
  • Understanding and applying CLT helps in decision-making based on sample data, facilitating accurate predictions and strategic planning in uncertain conditions.
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