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Data & Analytics · Intermediate

Two-Tailed Test

A hypothesis test in which the alternative is non-directional (≠), splitting α across both tails of the distribution.

Definition

With α = 0.05, each tail holds 0.025, so the critical z is ±1.96.

Exam tip

Two-tailed critical z at α = 0.05 is ±1.96; one-tailed is 1.645.

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