Central Limit Theorem simplified

Shanmugah Nagaraju
DataFrens.sg
Published in
3 min readJul 28, 2023

Statistics, as a science of extracting meaningful insights from data, relies on various concepts to make sense of the information at hand. One such concept that plays a important role in statistical analysis is the Central Limit Theorem (CLT).

Image by the author using Ipython Shell

Understanding the Central Limit Theorem

Central Limit Theorem states that when we have a sufficiently large sample size with a finite standard deviation, the sampling distribution of the sample mean for a variable will closely approximate a normal distribution, regardless of the underlying distribution of that variable in the population.

In simpler terms, imagine collecting multiple samples of data from a diverse population with different probability distributions, such as normal, left-skewed, right-skewed, or uniform. Now, if we calculate the mean for each of these samples and plot the distribution of those sample means, we will observe that it follows a bell-shaped, normal curve. This remarkable property holds true even when the original data may not be normally distributed.

The Role of Sample Size

As the sample size increases, the sampling distribution of the sample mean becomes increasingly similar to a normal distribution. This is a crucial aspect of the CLT, as it allows us to leverage the elegance and utility of the normal distribution’s statistics.

Mathematical Notation

Consider a random sample of size n, denoted by X1, X2,…. Xn, drawn from a population with a mean (μ) and a standard deviation (σ). When the sample size (n) is sufficiently large, typically considered to be n ≥ 30, the sampling distribution of the sample mean (X̅) will be approximately normal, with:

CLT properties by author

Practical Applications of the Central Limit Theorem

The Central Limit Theorem has great advantages in statistical practice. One of the key advantages is that it enables us to perform various tests, solve problems, and make inferences using the normal distribution, even when the population’s underlying distribution is unknown or non-normal.

In real-world applications, we often encounter situations where the true population distribution remains impossible to find. The CLT allow us to work with the familiar normal distribution, which simplifies statistical computations and analysis.

Unlocking the Power of the Normal Distribution

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The normal distribution’s unmatched applicability lies in its ability to calculate confidence intervals — a range of values within which we can be reasonably certain the true population parameter lies. Additionally, hypothesis testing becomes easy using the normal distribution’s clear properties.

Conclusion

In conclusion, the Central Limit Theorem stands as a important pillar of statistical analysis. Its ability to approximate normality in sampling distributions assists to draw meaningful insights and make informed decisions even when faced with diverse and unknown population distributions.

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Shanmugah Nagaraju
DataFrens.sg

Aspiring Data Scientist. Coding Noob. Learning to simplify the complexity. - Find me on LinkedIn: linkedin.com/in/shanmugah-nagaraju/