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 statistical power analysis calculator works
Power and planning use normal critical values with design-specific noncentral shifts.
Power is conditional on the effect, variability, alpha, allocation, and model specified before observing results.
Worked example
Statistical Power Analysis example
For a standardized two-group effect of 0.5 and 64 observations per group, approximate two-sided power is about 80%.
Power and planning use normal critical values with design-specific noncentral shifts.
Supported inputs
Precision and limits
Model and design
This planning approximation covers one mean, two equal-sized independent means, and paired means; final consequential designs need method-specific review.
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
Power is conditional on the effect, variability, alpha, allocation, and model specified before observing results.
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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