Transcript EPIB 698A lecture 1 Notes

EPIB 698C Lecture 1
Instructor: Raul Cruz-Cano
[email protected]
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Syllabus
What is SAS?
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SAS = “Statistical Analysis System” –
developed for both data manipulation and
data analyses in 1976
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Visit the SAS website: http://www.sas.com
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SAS vs Excel
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SAS is like a computer language
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Basics of SAS
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5 Windows
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EDITOR – file where you write code and comments for
execution by SAS (save as .sas)
LOG – file where notes about the execution of the program
are written, as well as errors (save as .log)
OUTPUT – file where results from the program are written
(save as .lst)
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Explorer Window
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Results Window
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The SAS interface consists of multiple windows designed for specific functions.
The following windows are open by default:
Enhanced Editor
Window
Type SAS programs here. The "enhanced" editor has
more advanced features than the traditional "program
editor" used in SAS 6.12.
Output Window
View the results of SAS procedures including
tables and line charts. Graphs will be displayed
in a separate Graph window.
Log
Window
View SAS programs as they
execute including error
messages and warnings.
Explorer
Window
Browse your SAS tables
(datasets) and libraries. Create
new files and file shortcuts.
Results
Window
Displays a hierarchical
outline of SAS results to
simplify output navigation.
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SAS Menus
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File: file input/output
Edit: Editing contents in every window
 Contents in LOG and OUTPUT windows are not
editable, but deletable
View: view programs, log files, outputs, and data sets
Tools: editors for graphics, report, table, etc
Solutions: analysis without writing codes
Window: navigating among windows
Help: help information of SAS
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SAS toolbar
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The toolbar gives you quick access to
commands that are already accessible
through the pull down menus
Not all operating environments have a
toolbar
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SAS command bar
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Command bar is a place where you can
type in SAS command.
Most commands you can type in the
command bar are accessible through
the SAS menus or the toolbar
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Controlling your windows
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The window pull-down menu
Type the name of the window in the
command bar
Click on the window
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Basic Rules of SAS Codes
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Every SAS statement ends with a semicolon ;
Lines of data are NOT separated by semicolons
SAS statements can extend over multiple lines
provided you do not split a word of the statement
across lines
More than one statement can appear on a single line
You can start statement anywhere within a line (not
recommended)
SAS is case insensitive, except for the values of
categorical variables
Words in SAS statement are separated by blanks
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SAS Steps
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Two main types of SAS steps:
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Data Step: read in data, manipulate datasets etc.
PROC Step: perform statistical analyses etc.
DATA and PROC steps execute when
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a RUN, QUIT, or CARDS statement is enters
Another DATA or PROC statement is entered
The ENDSAS statement is entered
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SAS Comments
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Two ways to comment:
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/* …..comments…..*/
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good for long documentation
 good for commenting out sections of code
*……comments……;
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good for commenting out one line of code
only commented until first ‘;’
SAS Comments are green in (SAS steps are blue)
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SAS Dataset
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Basic structure: a rectangular matrix
Name Sex
Age
Observation 1
Jane F
30
Observation 2
Mary F
29
Observation 3
Mike M
28
Columns are variables
Rows are observations
Example 1
/*Data instructor contains information of several
teachers*/
data instructor;
input name $ gender $ age;
cards;
Jane F 30
Mary F 29
Mike M 28
;
run;
Proc means;var age; run;
Part 1 of code
SAS data type
(1) Numeric data: numbers
• Can be added and subtracted
• Can have decimal places
• Can be positive or negative
(2) Character data: contains letters,
numerals or special characters
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SAS Dataset and variable
names
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Dataset name
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Start with A-Z or underscore character _
Can contain only letters, numbers, or underscores
Can contain upper- and lowercase letters
choose names which are easy to be memorized
Can be greater than 8 characters in SAS 8.0+
Variable name: same rule as dataset name
Examples: valid SAS names
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Parts
LastName
First_Name
_Null1_
X12
X1Y1
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Examples: invalid SAS names
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3Parts
Last Name
First-Name
_Null1$
Num%
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Submitting a program in SAS
First, get your program into the editor
 Type your program in the editor
 Open an existing SAS program: use
open from the File full down menu or
use the open icon or just click your SAS
program directly
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Submitting a program in SAS
Make your editor window active, and
submit your code by
 Submit Icon
 Enter submit in the command bar
 Select “submit” from the Run pull-down
menu
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Submitting a program in SAS
Reading the SAS log window
 It starts with notes about the version of
SAS and your SAS site number
 Original SAS code with line numbers
added on the left
 Notes contains information about SAS
data set and computer resources used
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Assessing errors in .log file
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Non-error SAS messages begin with NOTE:
SAS error message begin with ERROR: or possibly
WARNING:
In data set creation NOTE’s are important to read
because they indicate if the data set was created
correctly. Many times there are no errors yet the
data set is not correct.
ERROR message sometimes give you hints about
options or keywords in DATA/PROC steps
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The output window
Viewing results from the output window
 You can save and print contents in the
output window
 When you have a lot of output, one
easy way to find the specific output is
to use the list in the “results” window
Part 2 of code
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Creating HTML output
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Tools --- Options --Preferences
Click on the “Results” tab
Click the box next to “Create HTML”
Once turned on, results will be show in
the “Results Viewer” window
Results viewer window just show one
piece of output at a time
To turn off, just uncheck it
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SAS on Demand for Academics