# SAS - T Tests

The T-tests are performed to compute the confidence limits for one sample or two independent samples by comparing their means and mean differences.
The SAS procedure named **PROC TTEST** is used to carry out t tests on a single variable and pair of variables.

### Syntax

The basic syntax for applying PROC TTEST in SAS is −

PROC TTEST DATA = dataset; VAR variable; CLASS Variable; PAIRED Variable_1 * Variable_2;

Following is the description of the parameters used −

**Dataset**is the name of the dataset.**Variable_1 and Variable_2**are the variable names of the dataset used in t test.

### Example

Below we see one sample t test in which find the t test estimation for the variable horsepower with 95 percent confidence limits.

PROC SQL; create table CARS1 as SELECT make, type, invoice, horsepower, length, weight FROM SASHELP.CARS WHERE make in ('Audi','BMW') ; RUN; proc ttest data = cars1 alpha = 0.05 h0 = 0; var horsepower; run;

When the above code is executed, we get the following result −

## Paired T-test

The paired T Test is carried out to test if two dependent variables are statistically different from each other or not.

### Example

As length and weight of a car will be dependent on each other we apply the paired T test as shown below.

proc ttest data = cars1 ; paired weight*length; run;

When the above code is executed, we get the following result −

### Two sample t-test

This t-test is designed to compare means of same variable between two groups.

### Example

In our case we compare the mean of the variable horsepower between the two different makes of the cars("Audi" and "BMW").

proc ttest data = cars1 sides = 2 alpha = 0.05 h0 = 0; title "Two sample t-test example"; class make; var horsepower; run;

When the above code is executed, we get the following result −