Section 2.5: SAS Provides a Written Record of Your Work

One of the great strengths of SAS is its top-down functionality, which 
allows you to compose a sequence of DATA and PROC steps that together work 
to form an extended programming environment. Data can be read with a DATA 
step and analyzed in a PROC step, and the PROC step itself can write an 
output dataset that can be passed along to subsequent DATA or PROC steps.

Another nice feature of a SAS program is that it is 'self-documenting': 
SAS statements and your inserted comments provide a written record of what 
computations were done, and perhaps more importantly, what you didn't do. 
In many cases they can be repeated or quickly modified to analyze data of 
a similar structure.

The general flow of a SAS program is now briefly described. It usually 
begins with several statements that set up the working environment, format 
the printed output, specify directories of files, etc. (e.g. OPTIONS, 
TITLEn, LIBNAME, FILENAME etc.) followed by specific DATA and PROC steps 
to perform desired tasks.

OPTIONS <options> ;
TITLE1 ' <enter project title> ';

LIBNAME libref '<directory path of file location>';

* write one or more user defined formats;

PROC FORMAT;
VALUE fmta <formats>;   * numeric data;
VALUE $fmtb <formats>;  * character data ;
RUN;

* read data from an external file or an existing SAS dataset;

DATA <dataset_1>;
<SAS statements>;
RUN;

* perform desired analyses;

PROC <whatever_1> <options>;
<SAS statements>;
RUN;

PROC <whatever_2> <options>;
<SAS statements>;
RUN;

* modify the dataset written from the first DATA step;
* modify a dataset written by a previous PROC step;

DATA <dataset_2>;
SET <dataset_1>;
<SAS statements>;
RUN;

PROC <whatever_3> <options>;
<SAS statements>;
RUN;