Sample Size for Mean Calculator
Two-sided sample size for estimating a population mean: n = (z*sigma/E)^2 with z defaulting to 1.96.
Description
Two-sided sample size for estimating a population mean: n = (z*sigma/E)^2 with z defaulting to 1.96.
Sample Size for Mean Calculator is a focused tool for the following task. Two-sided sample size for estimating a population mean: n = (z*sigma/E)^2 with z defaulting to 1.96. It reports Required sample size, Exact sample size from the values you provide rather than inventing measurements, coefficients, or professional judgment that are not part of the input.
When to use Sample Size for Mean
Use this calculation to reproduce a defined quantitative method when the observations, units, sampling process, and assumptions match the method shown here.
- Population std dev
- Required number. Population standard deviation sigma.
- Margin of error
- Required number. Desired margin of error E on the mean.
- z score
- Optional number. Two-sided critical z value; defaults to 1.96 (95% confidence).
The cited overview of Statistics supplies background for the terminology and domain context used by this tool.1
How Sample Size for Mean works
Two-sided sample size for estimating a population mean: n = (z*sigma/E)^2 with z defaulting to 1.96. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.
- Required sample size
- Returned integer. Ceiling of the exact requirement.
- Exact sample size
- Returned number. Unrounded n = (z*sigma/E)^2.
Limitations and assumptions
- A numerical result does not by itself establish data quality, causation, representativeness, independence, distributional fit, or practical significance.
- Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.
Alternative or Complementary approaches
Inspect the underlying data, visualize its distribution, report uncertainty and sample size, and compare the result with a robust or domain-specific method where appropriate.
References
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Statistics — Wikipedia contributors
Similar or alternative tools
- Sample Size for Proportion Calculator
Two-sided sample size for estimating a proportion: n = p*(1-p)*(z/E)^2 with z defaulting to 1.96.
- T-Interval Calculator
Calculate a two-sided Student's t confidence interval for a population mean with unknown sigma.
- Z Confidence Interval Calculator
Calculate a two-sided confidence interval for a population mean when the population standard deviation is known.