You keep hearing me talk about SAS, but you may be thinking to yourself, “I don’t even know what SAS is.”
Well, in this video you’ll find out.
I’ll start with an overview of SAS software,
and then touch on its capabilities and uses.
You’ll also see a complete SAS program and some complete reports generated by SAS programs.
Over the next few weeks you’ll learn how to create this, and other similar, programs.
Finally, by the end of the course you’ll be able to write your own SAS programs,
and present your results in the form of an issue brief written for general audiences –
who may or may not have public health expertise.
But, before we discuss SAS let’s discuss something even more basic – data.
Here’s a question for you:
What is data?
Data is a collection of symbols, numbers, and letters recorded and stored in a way that
collectively represent some characteristics of an object or group of objects.
Here we have a table, which is a common way of organizing data.
Each box is called a cell.
Moving from left to right across the table are columns.
SAS uses the term “variables”.
SAS only recognizes two types of variables: Character and Numeric.
Numeric variables are numbers.
Character variables are letters, special characters, and numerals.
Numerals look like numbers, but they have no inherent numerical value to SAS.
Generally speaking, we will try to minimize the use of character variables in our SAS data sets.
More on this later.
The information contained in the first cell of each column is called the variable name.
Variable names can be no longer than 32 characters
and must begin with a letter or and underscore.
The remaining characters in the name may be letters, digits, or the underscore character.
Moving from top to bottom across the table are rows,
which are sometimes referred to as records.
SAS uses the terms “observations”.
The contents of each cell are called a value.
You should now be up to speed on some basic terminology used by SAS,
as well as other analytic, database, and spreadsheet programs.
These terms will be used repeatedly throughout the course.
But, you still haven't told us - what is SAS?
Well, SAS is a company that was created in the 1970’s.
The acronym originally stood for Statistical Analysis System.
But you know it as a computer program with its own programming language.
And once you learn to speak that language,
SAS can help you do all kinds of useful things.
Not that it’s very important for this class,
but for the sake of completeness I should probably also point out that SAS is not really one piece of software,
but many different pieces of software.
However, in this class we will primarily focus on base SAS.
And by the end of this course you will be able to independently use SAS to access data,
manage data,
analyze data,
and present data.
Let’s quickly take a closer look at each of these capabilities.
So what do we mean by “access data”.
Well, individuals and organizations store their data using different computer programs that store the data in different file types.
Some common examples are database files,
spreadsheets,
raw data files,
and SAS data sets.
No matter how the data is stored, you can’t do anything with it until you can get it into SAS,
in a form that SAS can use,
and in a location that you can reach.
In other words, accessing your data.
Therefore, among our first tasks in this course will be to access data.
Next, we’ll talk about managing data
Managing data can include: validating and cleaning data,
subsetting data,
creating new variables,
or combining data.
Basically this is just manipulating data so that you can analyze it.
This is probably the capability you most closely associate with SAS.
There is no doubt that SAS is a powerful tool for analyzing data.
However, in this class we won’t go much beyond using SAS to calculate basic descriptive statistics.
The ultimate goal is typically to present your findings in some form or another.
In SAS you can create many types of reports -
both tabular and graphical.
In this class you will learn how to create several of these reports,
and then learn how to enhance them.
You will also learn how to use SAS in conjunction with other software,
such as Microsoft Word, to create publishable manuscripts.
I’m going to show you some examples shortly.
But first, here’s a question for you: which of these SAS capabilities is most important?
Well, it’s hard to say.
They are probably all equally important.
But in my experience, you will probably spend more time on managing data than any other task.
Additionally, errors made during data management tend to be the most problematic, and hardest to detect.
In this demonstration I’m going to introduce you to some of the reports you can create using SAS.
Here we have a SAS program called, “01_First Demonstration”,
which is open in an enhanced editor window.
This program creates 6 different reports and one chart.
The reports and chart are based on North Texas Regional Health Department data for laboratory employees.
For now, don’t worry about any of the specifics of the
program, or of the different boxes open on the screen.
That information will all come in due time.
I just want you to get a feel for what a SAS program “does”.
The first report is in html format.
This report results from the print procedure, and it simply lists your data.
At the top of the screen you see the report title, and below the title is a table.
The first column in the table contains the observation, or obs, number,
which SAS includes automatically by default.
Following the obs column are the variables employee_id, job_title, salary, gender, birth_date, and manager_id.
As you glance over the table, notice that it includes numbers, letters, and dates.
Some of these values are pretty self-explanatory.
Others, like the values of job_title, are meaningless unless you are already familiar with the data.
In the second report you can see that the values are formatted, and much easier to interpret.
The data itself hasn’t changed, but the report now shows “Laboratory Assistant I” instead of simply showing “I”,
“Laboratory Assistant II” instead of “II” and so on.
You can also see that salaries are now more explicit,
and instead of simply showing “F” and “M”,
the report now shows the words “Female” and “Male”.
Looking over this report, what variable do you think the report is grouped by?
The report is grouped by gender.
It first lists all of the females, and then all of the males.
This report shows similar information, but it is displayed in the output window.
This type of output is referred to as listing output.
The fourth report is a frequency distribution of laboratory employees by job title.
In this report, which job title represents the highest percentage of the total?
10 people have the job title “Laboratory Assistant I”.
This makes up roughly 56% of all laboratory employees.
This report gives us some simple summary statistics about the salaries of laboratory employees.
What is the average salary of laboratory employees with the job title “Laboratory Assistant II”?
The average salary of laboratory employees with the job title, “Laboratory Assistant II” is $27,295 per year.
The sixth report our program created shows the results of the univariate procedure in html format.
Later, we will discuss this report in greater detail.
Finally, our program created a three dimensional bar chart in html format.
What do the height of the bars in this chart represent?
The height of the bars in this chart represent the number of men and women, grouped separately, with each job title.
This concludes your brief look at some sample reports in SAS.
You saw html and list reports,
frequency reports,
statistical reports,
and a chart.
In this demonstration we’re just going to open SAS in the Windows operating system.
Now there’s more than one way to open SAS,
but for now I’m going to show you how to open SAS using the start menu.
Watch as I click on the start menu, then on all
programs,
then on SAS,
and then on SAS 9.4.
If you are using a version of SAS other than 9.4, don’t worry about it.
It should open the exact same way.
When SAS opens, you will see the interactive SAS windowing environment.
This is the interface we will use throughout this course.
Notice the results and explorer windows on the left,
and the log and enhanced editor windows on the right.
The output window is also open, but it is behind the log and editor windows.
Generally, this is the interface you will use when you write SAS programs to perform programming tasks.
This interface provides tools for programming, including windows for entering and editing code,
checking the log and debugging programs,
viewing and managing output,
and viewing and managing SAS files.
Each time you start SAS, you see some messages in the log window,
including copyright notes and the version of SAS you are using.
One potentially important piece of information is the site number.
If you contact SAS technical support, they will request this site number.
What is the site number in the log window shown here?
The site number in the log window shown here is 70080564.
Here’s your fist practice opportunity. Good luck!