# Statistical power calculators

The power calculator computes the test power based on the sample size and draw an accurate power analysis chart.**Larger sample size increases the statistical power.**

Researchers usually use the power of **0.8** which mean the probability of type II error (β), failure to reject an incorrect H_{0.2}, is **0.2**. The commonly used significant level (α) is **0.05**. β is usually four times bigger than α, since rejecting a correct null assumption consider to be more severe than failing to reject a correct invalid assumption.