What does standard deviation tell me?

It measures how spread out a dataset is around the mean. A small SD means values cluster tightly; a large SD means they vary widely. About 68% of normally distributed values fall within ±1 SD of the mean.

What's the difference between population and sample SD?

Population SD divides by N (the number of data points). Sample SD divides by N−1 (Bessel's correction) to give an unbiased estimate of the population SD from a sample.

How is variance related?

Variance is the square of the standard deviation. SD is preferred for reporting because it's in the same units as the original data.

Standard Deviation Lommeregner 2026

Om standardafvigelsesberegneren

The Standard Deviation Calculator accepts any set of numbers and computes a full descriptive statistics summary. It distinguishes between population standard deviation (σ) — used when your data represents the entire population — and sample standard deviation (s) — used when your data is a sample from a larger population (divides by n−1 using Bessel's correction). All calculations run in your browser; no data is stored.

Formulas Used

Mean: μ = Σx / n

Population Variance: σ² = Σ(x − μ)² / n

Sample Variance: s² = Σ(x − μ)² / (n − 1)

Standard Deviation: σ = √σ² | s = √s²

What Does Standard Deviation Tell You?

Standard deviation measures the spread or dispersion of a data set. A low standard deviation means most values are close to the mean; a high standard deviation means values are spread over a wider range. It is one of the most fundamental tools in statistics, used in science, finance, quality control, and social research.

Population vs. Sample Standard Deviation

Use population standard deviation (σ) when you have data for the entire group you are studying — for example, the test scores of all students in a specific class. Use sample standard deviation (s) when your data is a subset of a larger population — for example, a random sample of 50 employees from a company of 5,000. Sample SD uses n−1 in the denominator to correct for the underestimation of variance that occurs with small samples.

Andre beregnede statistikker

Mean (average) — the central value of the data set
Median — the middle value when sorted; less sensitive to outliers than the mean
Range — the difference between the maximum and minimum values
Variance — the square of the standard deviation, useful for statistical tests
Count (n) — antallet af datapunkter indtastet

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Vigtig bemærkning: Dette værktøj er beregnet til at give estimater og bør ikke bruges som erstatning for professionel rådgivning. Oplysninger genereret af disse lommeregnere kan være ufuldstændige og tager ikke højde for alle individuelle omstændigheder. Søg altid rådgivning fra en certificeret ekspert (som en finansiel rådgiver, sundhedsperson eller licenseret ingeniør), inden du handler baseret på disse resultater.

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📊 Standardafvigelse-lommeregner