Standard Deviation of Sample Mean Calculator

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Results

Standard deviation of the sample mean (σX̄)

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What is Standard Deviation?

The standard error describes the variability of sample means under repeated independent sampling.

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How to Use This Calculator

  1. Enter or select Population standard deviation (σ), Sample size (n).
  2. Check the unit beside each measurement. For a percentage or rate, use the scale and time period stated in the form.
  3. Choose Calculate, then compare the output with the formula and example below. If you change a value or option, calculate again to update the result.
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Formula Used

SE = σ/√n
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Variables Explained

InputWhat it means
Population standard deviation (σ)The spread of individual observations around their mean, in the data’s original units.
Sample size (n)Number of observations or responses in the sample, rather than the population size.
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Worked Example

Population standard deviation 12 with sample size 36 gives SE=2.

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Why Use This Calculator?

Estimate how much an average may vary across independent samples.

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Common Mistakes

    • This is the spread of sample means, not the spread of individual observations.
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Frequently Asked Questions

Does a calculated statistic prove a conclusion?

A statistic describes the supplied data under stated assumptions. Sampling design, missing observations and the suitability of the model still determine what can reasonably be concluded.

Should I include every observation?

Use the observations required by your study design and state any exclusion rule. Removing values only because they change the answer can bias the analysis.

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Sources & References