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Central limit theorem simulator

Paste population values and set sample size and repetitions.

Simulated SD of sample means: —

Fill in the fields above — the result is computed on this page.

Population mean
—
Population sample SD
—
Expected standard error
—
Mean of sample means
—
Repetitions
—

Histogram of sample means

From To Samples Share
Fill in the fields above — the result is computed on this page.
What these numbers mean
  • Compare simulated SD of means with σ/√n.
  • Increase n and watch the histogram narrow.
  • Strongly skewed populations may require larger n.

Simulation does not prove normality for a particular small sample. Dependence, infinite-variance heavy tails and unrepresentative data violate the model.

How to use this page
  1. Paste a finite population or empirical distribution.
  2. Set n, repetitions and seed.
  3. Compare the histogram with theoretical and simulated standard errors.

What this page does not do: Simulation does not prove normality for a particular small sample. Dependence, infinite-variance heavy tails and unrepresentative data violate the model.

Further reading

The central limit theorem says that, under its assumptions, the mean of large samples approaches a normal distribution even when the population is not normal. Its centre tends to μ and its standard deviation to σ/√n.

The simulator samples with replacement from the entered empirical population. This demonstrates convergence, but one simulation remains random and seed-dependent.

Frequently asked questions

Why use a random seed?

The same seed reproduces the experiment, making settings comparable.

Is n = 30 always enough?

No. Required size depends on skewness, tails, dependence and the analysis goal.

See also

← All calculators

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