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 birnbaum–saunders distribution calculator works
F(x)=Φ({√(x/β)−√(β/x)}/α), x>0, with shape α and scale β.
The model was developed for positive fatigue-life behavior and its scale parameter is the median, not the mean.
Worked example
Birnbaum–Saunders Distribution example
For any positive shape, x equal to scale β is the median because the transformed normal score is zero.
F(x)=Φ({√(x/β)−√(β/x)}/α), x>0, with shape α and scale β.
Supported inputs
Precision and limits
Model and design
The calculator uses the standard shape α and scale β convention; fatigue mechanism, censoring, and goodness of fit are not assessed.
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 model was developed for positive fatigue-life behavior and its scale parameter is the median, not the mean.
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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