TDIST function

Returns the Percentage Points (probability) for the Student t-distribution where a numeric value (x) is a calculated value of t for which the Percentage Points are to be computed. The t-distribution is used in the hypothesis testing of small sample data sets. Use this function in place of a table of critical values for the t-distribution.

Syntax

TDIST(x,degrees_freedom,tails)

X     is the numeric value at which to evaluate the distribution.

Degrees_freedom     is an integer indicating the number of degrees of freedom.

Tails     specifies the number of distribution tails to return. If tails = 1, TDIST returns the one-tailed distribution. If tails = 2, TDIST returns the two-tailed distribution.

Remarks

• If any argument is nonnumeric, TDIST returns the #VALUE! error value.

• If degrees_freedom < 1, TDIST returns the #NUM! error value.

• The degrees_freedom and tails arguments are truncated to integers.

• If tails is any value other than 1 or 2, TDIST returns the #NUM! error value.

• TDIST is calculated as TDIST = p( x<abs(X)), where X is a random variable that follows the t-distribution.

Examples

X	Degrees	Formula	Description (Result)
1.96	60	=TDIST([X],[Degrees],2)	Two-tailed distribution (0.054644927 or 5.46 percent)
1.96	60	=TDIST([X],[Degrees],1)	One-tailed distribution (0.027322463 or 2.73 percent)