Question 1

What is a Statistical Power?

Accepted Answer

Statistical power (1−β) is the probability of correctly detecting a true effect. Power of 0.80 (80%) is the conventional minimum — a 20% chance of missing a real effect (Type II error).

Question 2

How does the Statistical Power work?

Accepted Answer

Power increases with: larger n, larger effect size, higher α Then: Plan sample size to achieve 80% power before collecting data Then: Power = Φ(|d|√(n/2) − z_α).

Question 3

Can you give an example of how to use the Statistical Power?

Accepted Answer

Example: Input d=0.5 · n=50/group · α=0.05 gives a result of Power ≈ 70% — underpowered (Need ~64/group for 80% power).

Question 4

Is the Statistical Power free to use?

Accepted Answer

Yes — completely free with no registration, download, or subscription required. All calculations happen instantly in your browser.

Question 5

How accurate is the Statistical Power?

Accepted Answer

Our Statistical Power uses verified mathematical formulas and is accurate to multiple decimal places. Results are calculated in real-time using the same methods used by professionals.

Question 6

What statistical method does this Statistical Power use?

Accepted Answer

This calculator uses industry-standard statistical formulas. For research use, always report your full methodology including sample size, confidence levels, and any assumptions made.

Statistical Power

📊Statistical Power Calculator

What is Statistical Power?

How to Use Statistical Power

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