Quick guide
How to use this calculator
- Enter the observations, probabilities, model parameters, or summary statistics requested by the visible labels.
- Keep every value on the same scale and confirm that the selected sampling relationship, distribution, and tail convention match the question you are investigating.
- Read the result together with its assumptions and interpretation. Statistical output summarizes uncertainty under a model; it does not repair biased data or establish causation.
Calculation method
How the half-normal distribution calculator works
F(x)=2Φ(x/σ)−1 for x≥0, where σ is the parent normal standard deviation.
The half-normal model describes nonnegative magnitudes produced by folding a zero-centered normal variable at zero.
Worked example
Half-Normal Distribution example
With σ=1, the cumulative probability at x=1 is 2Φ(1)−1≈0.682689.
F(x)=2Φ(x/σ)−1 for x≥0, where σ is the parent normal standard deviation.
Supported inputs
Precision and limits
Model and design
Scale σ belongs to the unobserved parent normal and is not the half-normal standard deviation; shifted folded normals are outside this scope.
Numerical scope
Inputs use double-precision numerical methods with guarded domains. Datasets accept up to 10,000 finite plain-decimal values. Extremely large parameters or probabilities deep in a numerical tail may require specialist statistical software.
Interpretation
The half-normal model describes nonnegative magnitudes produced by folding a zero-centered normal variable at zero.
Decision boundary
The calculator does not validate how data were collected, diagnose dependence or bias, choose a scientifically meaningful effect, or replace review by a qualified statistician for consequential research, medical, regulatory, safety, or policy decisions.
Privacy
Entered values and calculated results stay in this browser and are not sent to an analytics service.
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