**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: