**Standard deviation (SD)** is a measure of how varied is the data in a data set. Mathematically it measures how distant or close are each value to the mean value of a data set. A standard deviation value close to 0 indicates that the data points tend to be very close to the mean of the data set and a high standard deviation indicates that the data points are spread out over a wider range of values

In SAS the SD values is measured using PROC MEAN as well as PROC SURVEYMEANS.

**Using PROC MEANS**

To measure the SD using **proc means** we choose the STD option in the PROC step. It brings out the SD values for each numeric variable present in the data set.

**Syntax**

The basic syntax for calculating standard deviation in SAS is:

PROC means DATA = dataset STD;

Following is the description of the parameters used:

Dataset is the name of the dataset.

**Example**

In the below example we create the data set CARS1 form the CARS data set in the SASHELP library. We choose the STD option with the PROC means step.

PROC SQL;

create table CARS1 as

SELECT make,type,invoice,horsepower,length,weight

FROM

SASHELP.CARS

WHERE make in (‘Audi’,’BMW’)

;

RUN;

proc means data=CARS1 STD;

run;

When we execute the above code it gives the following output:

**Using PROC SURVEYMEANS**

This procedure is also used for measurement of SD along with some advance features like measuring SD for categorical variables as well as provide estimates in variance.

**Syntax**

The syntax for using PROC SURVEYMEANS is:

PROC SURVEYMEANS options statistic-keywords ;

BY variables ;

CLASS variables ;

VAR variables ;

Following is the description of the parameters used :

**BY**indicates the variables used to create groups of observations.**CLASS**indicates the variables used for categorical variables.**VAR**indicates the variables for which SD will be calculated.

**Example**

The below example describes the use of class option which creates the statistics for each of the values in the class variable.

proc surveymeans data=CARS1 STD;

class type;

var type horsepower;

ods output statistics=rectangle;

run;

proc print data=rectangle;

run;

When we execute the above code it gives the following output:

**Using BY option**

The below code gives example of BY option. In it the result is grouped for each value in the BY option.

**Example**

proc surveymeans data=CARS1 STD;

var horsepower;

BY make;

ods output statistics=rectangle;

run;

proc print data=rectangle;

run;

When we execute the above code it gives the following output:

Result for make = “Audi”

Result for make = “BMW”