Syntax
T.INV(probability, deg_freedom)
| Parameter | Description |
|---|---|
| probability | Parameter of the T.INV function. |
| deg_freedom | Parameter of the T.INV function. |
Examples
Critical value for 95% CI (lower bound)
Formula
=T.INV(0.025, 24)
Returns ~-2.0639. This is the negative critical value for the lower bound of a 95% confidence interval with 24 degrees of freedom.
One-tailed critical value at 5%
Formula
=T.INV(0.95, 10)
Returns ~1.8125. For a one-tailed test at the 5% significance level with 10 df, the critical value is about 1.81.
50th percentile
Formula
=T.INV(0.5, 30)
Returns 0. The t-distribution is symmetric around zero, so the 50th percentile is always 0 regardless of degrees of freedom.
Common Errors
#NUM!
Probability must be between 0 and 1 (exclusive) and degrees of freedom must be at least 1.
#VALUE!
Occurs when arguments are non-numeric.
Tips
For confidence intervals
To get the critical value for a 95% CI, use T.INV(0.025, df) for the lower bound and T.INV(0.975, df) for the upper bound. Or use T.INV.2T(0.05, df) for the positive value directly.
Left-tailed, not two-tailed
T.INV returns the left-tail inverse. For two-tailed critical values (the most common need), use T.INV.2T instead.
Returns negative for p < 0.5
Unlike T.INV.2T which always returns a positive value, T.INV can return negative values when the probability is below 0.5.
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