Statistical Power Calculator
Calculate statistical power and required sample size for hypothesis testing
About this calculator
A Statistical Power Calculator helps researchers determine the probability of detecting a true effect in their study and calculate the minimum sample size needed for reliable results. Statistical power analysis is essential for designing robust experiments, securing research funding, and avoiding underpowered studies that waste resources. This tool enables researchers to balance statistical rigor with practical constraints by optimizing study design parameters before data collection begins.
How to use
Enter your desired statistical power level (typically 0.8), significance level (usually 0.05), and expected effect size based on literature or pilot studies. The calculator will determine the required sample size, or input your available sample size to calculate the statistical power your study will achieve.
Frequently asked questions
What is statistical power?
Statistical power is the probability of correctly detecting a true effect when it exists, typically set at 0.8 or 80% in research studies.
What effect size should I use?
Use effect sizes from similar studies, pilot data, or standardized conventions (small=0.2, medium=0.5, large=0.8 for Cohen's d).
Why is sample size calculation important?
Proper sample size ensures adequate power to detect meaningful effects while avoiding unnecessarily large studies that waste time and resources.