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Data & Analytics · Foundational

Significance Level (α)

The threshold probability α for rejecting the null hypothesis, commonly 0.05, which equals the accepted Type I error rate.

Definition

α is chosen before testing. A 95% confidence level corresponds to α = 0.05 in a two-sided test.

Exam tip

Lowering α reduces false positives but increases false negatives (Type II errors).

Related terms