Syntax
TDIST(x, deg_freedom, tails)
| Parameter | Description |
|---|---|
| x | Parameter of the TDIST function. |
| deg_freedom | Parameter of the TDIST function. |
| tails | Parameter of the TDIST function. |
Examples
Two-tailed p-value for t=2.1
Formula
=TDIST(2.1, 25, 2)
Returns ~0.0459. The two-tailed p-value is about 4.6%, just below the 5% significance threshold.
One-tailed p-value
Formula
=TDIST(1.8, 10, 1)
Returns ~0.0509. The one-tailed p-value is about 5.1%, just above the 5% significance level.
Testing a large sample
Formula
=TDIST(3, 100, 2)
Returns ~0.0034. With 100 degrees of freedom and t=3, the result is highly significant (p < 0.01).
Common Errors
#NUM!
x must be non-negative (TDIST only accepts positive values, unlike T.DIST). Tails must be 1 or 2.
#VALUE!
Occurs when arguments are non-numeric.
Tips
Tails argument: 1 or 2
Set tails=1 for a one-tailed test (right tail only) or tails=2 for a two-tailed test. There is no option for left-tail only — use T.DIST for that.
x must be positive
Unlike T.DIST, TDIST requires x >= 0. If your test statistic is negative, use its absolute value since the t-distribution is symmetric.
Migrate to T.DIST family
For new work, use T.DIST (left CDF), T.DIST.RT (right tail), or T.DIST.2T (two-tailed) for more explicit control over which tail you are computing.
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