About This Book
Who needs this book This book is for all new SAS users in business, government, and academia, and for anyone who will be conducting data analysis using SAS software. You need no prior experience with SAS, but if you have some experience you may still find this book useful for learning techniques you missed or for reference.
What this book covers This book introduces you to the SAS language with lots of practical examples, clear and concise explanations, and as little technical jargon as possible. Most of the features covered here come from Base SAS, which contains the core of features used by all SAS programmers. One exception is Chapter 9, which includes procedures from SAS/STAT. Other exceptions appear in Chapters 2 and 10, which cover importing and exporting data from other types of software; some methods require SAS/ACCESS Interface to PC Files.
We have tried to include every feature of Base SAS that a beginner is likely to need. Some readers may be surprised that certain topics, such as macros, are included because they are normally considered advanced. But they appear here because sometimes new users need them. However, that doesn’t mean that you need to know everything in this book. On the contrary, this book is designed so that you can read just those sections you need to solve your problems. Even if you read this book from cover to cover, you may still find yourself returning to refresh your memory as new programming challenges arise.
What this book does not cover To use this book you need no prior knowledge of SAS, but you must know something about your local computer and operating environment. The SAS language is virtually the same from one operating environment to another, but some differences are unavoidable. For example, every operating environment has a different way of storing and accessing files. Your employer may have rules such as limits for the size of files that you can print. This book addresses operating environments when relevant, but no book can answer every question about your local system. You must have either a working knowledge of your computer system or someone you can turn to with questions.
As a SAS programmer, you have a choice about which interface you use to write your programs, and how you run them. This edition of The Little SAS Book is designed to work with all of the interfaces that are included with Base SAS: SAS Studio, SAS Enterprise Guide, and the SAS windowing environment (also known as Display Manager), in addition to batch submission. (SAS University Edition and SAS OnDemand for Academics use the SAS Studio interface.) Each of these methods offers its own unique set of features. This book mentions a few of the differences, but is not a comprehensive introduction. See Section 1.5 for a brief description of each method and recommendations about how to learn more.
This book is not a replacement for the SAS Documentation, or the many SAS publications. We encourage you to turn to them for details that are not covered in this book. You can find the complete SAS Documentation at SAS Institute’s support website:
We cover only a few of the many SAS statistical procedures. Fortunately, the statistical procedures share many of the same statements, options, and output, so these few can serve as an introduction to the others. Once you have read Chapter 9, we think that other statistical procedures will feel familiar.
Unfortunately, a book of this type cannot provide a thorough introduction to statistical concepts such as degrees of freedom, or crossed and nested effects. There are underlying assumptions about your data that must be met for the tests to be valid. Experimental design and careful selection of models are critical. Interpretation of the results can often be difficult and subjective. We assume that readers who are interested in statistical computing already know something about statistics. People who want to use statistical procedures but are unfamiliar with these concepts should consult a statistician, seek out an introductory statistics text, or, better yet, take a course in statistics.
Modular sections Our goal in writing this book is to make learning SAS as easy and enjoyable as possible. Let’s face it—SAS is a big topic. You may have already spent some time staring at a screen full of documentation until your eyes become blurry. We can’t condense all of SAS into this little book, but we can condense topics into short, readable sections.
This entire book consists of two-page sections, each section a complete topic. This way, you can easily skip over topics that do not apply to you. Of course, we think every section is important, or we would not have included it. You probably don’t need to know everything in this book, however, to complete your job. By presenting topics in short digestible sections, we believe that learning SAS will be easier and more fun—like eating three meals a day instead of one giant meal a week.
Graphics Wherever possible, graphic illustrations either identify the contents of the section or help explain the topic. A box with rough edges indicates a raw data file, and a box with nice smooth edges indicates a SAS data set. The squiggles inside the box indicate data—any old data—and a period indicates a missing value. The arrow between boxes of these types means that the section explains how to get from data that look like one box to data that look like the other. Some sections have graphics that depict printed output. These graphics look like a stack of papers with headers printed at the top of the page.
Typographical conventions SAS doesn’t care whether your programs are written in uppercase or lowercase, so you can write your programs any way you want. In this book, we have used uppercase and lowercase to tell you something. The statements on the left below show the syntax, or general form, while the statements on the right show an example of actual statements as they might appear in a SAS program.
Syntax |
Example |
PROC PRINT DATA = data-set-name; |
PROC PRINT DATA = bigcats; |
Notice that the keywords PROC PRINT, DATA, and VAR are the same on both sides and that the descriptive terms data-set-name and variable-list on the syntax side have been replaced with an actual data set name and variable names in the example.
In this book, all SAS keywords appear in uppercase letters. A keyword is an instruction to SAS and must be spelled correctly. Anything written in lowercase italics is a description of what goes in that spot in the statement, not what you actually type. Anything in lowercase or mixed case letters (and not in italics) is something that the programmer has made up such as a variable name, a name for a SAS data set, a comment, or a title. See Section 1.2 for further discussion of the significance of case in SAS names.
Indention This book contains many SAS programs, each complete and executable. Programs are formatted in a way which makes them easy for you to read and understand. You do not have to format your programs this way, as SAS is very flexible, but attention to some of these details will make your programs easier to read. Easy-to-read programs are time-savers for you, or the consultant you hire at $200 per hour, when you need to go back and decipher the program months or years later.
The structure of programs is shown by indenting all statements after the first in a step. This is a simple way to make your programs more readable, and it’s a good habit to form. SAS doesn’t really care where statements start or even if they are all on one line. In the following program, the INFILE and INPUT statements are indented, indicating that they belong with the DATA statement:
* Read animals’ weights from file. Print the results.;
DATA animals;
INFILE 'c:MyRawDataoo.dat';
INPUT Lions Tigers;
RUN;
PROC PRINT DATA = animals;
RUN;
Data and programs used in this book You can access the data and programs that are used in the examples by linking to either of the author pages for this book at:
or
From there, you can select Example Code and Data to download a file containing the data and programs from this book.
Last, we have tried to make this book as readable as possible and, we hope, even enjoyable. Once you master the contents of this small book you will no longer be a beginning SAS programmer.