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Statistical function

T.INV.2T

Returns the two-tailed inverse of the Student t distribution: the critical t for a confidence level.

Rarely usedDifficulty 1500 · AdvancedUsage rank #413 of 520
Practice · 2 questions →

When to use it

The two-tailed t critical value: the t a statistic must exceed in absolute value to be significant at alpha.

The shape of it

Syntax
=T.INV.2T(probability, deg_freedom)

Worked examples

  • 5%, 10 df

    =T.INV.2T(0.05,10) 2.228138852

    5% on 10 degrees of freedom.

  • 5%, 30 df

    =T.INV.2T(0.05,30) 2.042272456

    Closer to 1.96 as df grow.

  • 1%, 10 df

    =T.INV.2T(0.01,10) 3.169272673

    1% on 10 degrees of freedom.

Worth knowing

  • Interval half-width: T.INV.2T(0.05,n-1)*sd/SQRT(n), the same as CONFIDENCE.T.
  • Replaces TINV.
  • Always positive.

Where it goes wrong

  • #NUM! for probability outside 0 to 1.
  • Confusing it with T.INV gives a value at the wrong probability.

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