You can use the TINV function in SAS to find critical values from the t distribution.
This function uses the following basic syntax:
TINV(p, df)
where:
- p: 1 – the significance level
- df: The degrees of freedom
The following example shows how to use the TINV function to find the t critical value for a left-tailed test, right-tailed test, and a two-tailed test.
Example 1: Using TINV Function for Left-Tailed Test
Suppose we want to find the t critical value for a left-tailed test with a significance level of .05 and degrees of freedom = 22:
We can use the TINV function to calculate this value:
/*create dataset that contains t critical value*/
data my_data;
critical_val=tinv(.05, 22);
put critical_val=;
run;
/*view results*/
proc print data=my_data;
The t critical value for a significance level of 0.05 and degrees of freedom = 22 is -1.71714.
Thus, if the test statistic is less than this value then the results of the test are statistically significant.
Example 2: Using TINV Function for Right-Tailed Test
Suppose we want to find the t critical value for a right-tailed test with a significance level of .05 and degrees of freedom = 22:
We can use the TINV function to calculate this value:
/*create dataset that contains t critical value*/
data my_data;
critical_val=tinv(.95, 22);
put critical_val=;
run;
/*view results*/
proc print data=my_data;
The t critical value for a significance level of 0.05 and degrees of freedom = 22 is 1.71714.
Thus, if the test statistic is greater than this value then the results of the test are statistically significant.
Example 3: Using TINV Function for Two-Tailed Test
Suppose we want to find the t critical value for a two-tailed test with a significance level of .05 and degrees of freedom = 22:
We can use the TINV function to calculate this value:
/*create dataset that contains t critical value*/
data my_data;
critical_val=tinv(.05/2, 22);
put critical_val=;
run;
/*view results*/
proc print data=my_data;
Whenever you perform a two-tailed test, there will be two critical values. In this case, the t critical values are -2.07387 and 2.07387.
Thus, if the test statistic is less than -2.0739 or greater than 2.0739 then the results of the test are statistically significant.
Additional Resources
The following tutorials explain how to perform other common tasks in SAS:
How to Perform a One Sample t-Test in SAS
How to Perform a Two Sample t-Test in SAS
How to Perform a Paired Samples t-Test in SAS