1. SAS Programming II Matthew A. Lanham Doctoral Student
September 17, 2018
SAS Programming II
Matthew A. Lanham
Doctoral Student
Virginia Polytechnic Institute and State University
Pamplin College of Business
Department of Business Information Technology

2. September 17, 2018

3. Short Course Outline Load in Data Sets From Yesterday
SAS Programming II
September 17, 2018
Short Course Outline
Load in Data Sets From Yesterday
Changing Data From Numeric to Character and Vise-Versa
Review of DATA and PROC steps
Data Example: National Longitudinal Mortality Survey
PROC TTEST, PROC NPAR1WAY, PROC FREQ
SQL
PROC SQL
Basic Plotting Examples
SAS Macros
References
September 17, 2018
05:28

4. Lets get our Data Sets From Yesterday Loaded
Load Data
SAS Programming II
September 17, 2018
Lets get our Data Sets From Yesterday Loaded
Drag your SAS_LISA_2.sas code into the Enhanced Editor Window
Highlight lines 1 through 132
Select Run
September 17, 2018
05:28

5. Changing Data Types – PUT
SAS Programming II
September 17, 2018
Changing Data Types – PUT
You can convert a Numeric variable to a Character variable by using the PUT function:
General Form:
new_variable = PUT(current_variable, new_format);
DROP current_variable;
RENAME new_variable = current_variable;
September 17, 2018
05:28

6. Changing Data Types – INPUT
SAS Programming II
September 17, 2018
Changing Data Types – INPUT
You can convert a Character variable to a Numeric variable by using the INPUT function:
General Form:
new_variable = INPUT(current_variable, new_format);
DROP current_variable;
RENAME new_variable = current_variable;
September 17, 2018
05:28

7. National Longitudinal Mortality Survey
NLMS
SAS Programming II
September 17, 2018
National Longitudinal Mortality Survey
Survey given by the Census Bureau.
Public access data -
This is the 3rd release (June 1, 2008)
38 variables; 988,346 observations
September 17, 2018
05:28

8. Lets see what our NLMS data says about this…
Using NLMS data
SAS Programming II
September 17, 2018
Lets see what our NLMS data says about this…
Probably a meta-analysis
60 years!! That’s a long time ago
September 17, 2018
05:28

9. Two-sample t-test
SAS Programming II
September 17, 2018
PROC TTEST
A two-sample t-test allows us to test for statistical significance between two groups.
Standard assumptions: (1) IID (“random”) samples, (2) Normally distributed, (3) Equal variances
General Form:
Two-sided test: 𝐻 1 : 𝜇 𝑚𝑎𝑟𝑟𝑖𝑒𝑑_𝑚𝑎𝑙𝑒 ≠ 𝜇 𝑢𝑛𝑚𝑎𝑟𝑟𝑖𝑒𝑑_𝑚𝑎𝑙𝑒
One-sided test: 𝐻 1 : 𝜇 𝑚𝑎𝑟𝑟𝑖𝑒𝑑_𝑚𝑎𝑙𝑒 > 𝜇 𝑢𝑛𝑚𝑎𝑟𝑟𝑖𝑒𝑑_𝑚𝑎𝑙𝑒
PROC TTEST data=libref.filename;
CLASS <variable that classifies set into two groups>
VAR <variable that is measured>
RUN;
September 17, 2018
05:28

10. PROC TTEST Assumptions: (1) IID (“random”) samples
Two-sample t-test
SAS Programming II
September 17, 2018
PROC TTEST
Assumptions: (1) IID (“random”) samples
(2) Normally distributed could try non-parametric test
(3) Equal variances Use unequal variance test (Satterthwaite)
Since we have unequal variances, we would make any conclusions using the unequal t-test
The F-test is what you use to test
for equal variances:
𝐻 1 : 𝜎 𝑚𝑚 = 𝜎 𝑢𝑚 𝑣𝑠. 𝐻 1 : 𝜎 𝑚𝑚 ≠ 𝜎 𝑢𝑚
September 17, 2018
05:28

11. PROC FREQ or PROC NPAR1WAY
Wilcoxon rank sum test
SAS Programming II
September 17, 2018
PROC FREQ or PROC NPAR1WAY
Parametric methods of statistical inference require you to assume that your data come from some underlying probability distribution (in our case Normal)
Nonparametric methods relax underlying assumptions about how the data is generated, because maybe you don’t know or the parametric assumptions are not satisfied.
Nonparametric equivalent to two-sample t-test is: Wilcox rank sum test (Wilcoxon-Mann-Whitney Test)
Standard assumptions: (1) I hope this works or my dissertation is shot!
General Forms:
PROC FREQ data=libref.filename <options>;
TABLES group*measure / <options>;
RUN;
PROC NPAR1WAY data=libref.filename <options>;
CLASS <variable that classifies set into two groups>
VAR <variable that is measured>
RUN;
September 17, 2018
05:28

12. PROC FREQ and PROC NPAR1WAY
Wilcoxon rank sum test
SAS Programming II
September 17, 2018
PROC FREQ and PROC NPAR1WAY
𝐻 1 :𝑑𝑖𝑠 𝑡 ′ 𝑛 𝑜𝑓 𝑚𝑚≠𝑑𝑖𝑠𝑡𝑛 𝑜𝑓 𝑢𝑚
We can conclude there is a difference in life expectancy among married men versus unmarried men.
September 17, 2018
05:28

13. Me in 20 years… Pursue Industry
Old age..
SAS Programming II
September 17, 2018
Me in 20 years…
Looks like Kim has a lot to look forward
to either way.
Pursue Industry
Academic
Life
September 17, 2018
05:28

14. SQL SQL (pronounced “SEQUEL”) means Structured Query Language
SAS Programming II
September 17, 2018
SQL
SQL (pronounced “SEQUEL”) means Structured Query Language
The language used by relational database management systems (RDMS)
Examples: Microsoft Access, MySQL, Oracle, PostgreSQL, SQL Server,…
General Form:
Example: Database Table called Employee
SELECT <specifies the columns to be selected>
FROM <database table or libref.libname to be queried>
WHERE <subsets the data on a condition>
GROUP BY <variables used in functions>
HAVING <a filter for thos e variables in the GROUP BY>
ORDER BY <variables to order by>
Note: You will always have at least a SELECT and a FROM
SELECT Name, Salary
FROM Employee
WHERE ID >=200 AND Salary >48000
September 17, 2018
05:28

15. PROC SQL
SAS Programming II
September 17, 2018
PROC SQL
PROC SQL allows you to treat your SAS Data Sets like Database tables.
General Form:
Does not require
a RUN;
PROC SQL;
SELECT <specifies the columns to be selected>
FROM <database table or libref.libname to be queried>
WHERE <subsets the data on a condition>
GROUP BY <variables used in functions>
HAVING <a filter for thos e variables in the GROUP BY>
ORDER BY <variables to order by>;
QUIT;
Select * means select all columns
Instead of desc, you could also use asc
September 17, 2018
05:28

16. Creating a New Variable or New Table
PROC SQL
SAS Programming II
September 17, 2018
Creating a New Variable or New Table
Healthy average male weight (5’11, 65+) is approximately 181 pounds.
Here we can create a new variable called “pct_above_avg” using AS:
General Form:
PROC SQL;
CREATE TABLE libref.libname AS
SELECT <specifies the columns to be selected>
FROM <database table or libref.libname to be queried> ….
QUIT;
September 17, 2018
05:28

17. Querying Multiple Tables
PROC SQL
SAS Programming II
September 17, 2018
Querying Multiple Tables
PROC SQL allows you to examine data stored in two tables. Combining tables horizontally is called “joining.” Joins do not alter tables!
General Form:
PROC SQL;
SELECT libname.variable2, libname.variable2
FROM libref.libnameA, libref.libnameB
WHERE libnameA.variable1 = libnameB.variable1;
QUIT; A
lisa.B
September 17, 2018
05:28

18. Querying Multiple Tables
PROC SQL
SAS Programming II
September 17, 2018
Querying Multiple Tables
This example also shows how to do a many-to-many match merge which is not available using the standard MERGE in a DATA step.
General Form:
PROC SQL;
SELECT libname.variable2, libname.variable2
FROM libref.libnameA, libref.libnameB
WHERE libnameA.variable1 = libnameB.variable1;
QUIT;
September 17, 2018
05:28

19. PROC SQL
SAS Programming II
September 17, 2018
Group By
Use a Group By when you are performing some aggregation function in the SELECT clause like sum(), count(), avg()
September 17, 2018
05:28

20. Basic plotting Examples
SAS Programming II
September 17, 2018
Basic plotting Examples
SGPLOT makes some nice plots. Here are couple quick examples.
Histogram
Side-by-side Box Plots
September 17, 2018
05:28

21. SAS Macros General Form: When using %LET:
SAS Programming II
September 17, 2018
SAS Macros
SAS macro variables enable you to substitute text in your SAS programs.
When you reference a macro variable in a SAS program, SAS replaces the reference with the text value that has been assigned to that macro variable. This in turn will enable your programs to become more reusable and dynamic.
The first thing you want to do is create a LET statement.
General Form:
When using %LET:
All values are stored as character strings
Mathematical expressions are not evaluated
The case of the value is preserved
Quotation marks that enclose literals are stored as part of the value
Leading and trailing blanks are removed from the value before assignment is made
%LET variable =value;
September 17, 2018
05:28

22. SAS Macros General Form: When using %PUT:
SAS Programming II
September 17, 2018
SAS Macros
A %PUT statement writes text to the SAS log.
General Form:
When using %PUT:
Writes only to the SAS log
Always writes to a new log line, starting in column one
Writes blank line if text is not specified
Does not require quotation marks around text
Can be used either inside or outside a macro definition
The %INDEX function – enables you to determine the position of the first character of a string within another string.
%PUT text;
September 17, 2018
05:28

23. Macros
SAS Programming II
September 17, 2018
SAS Macros
Like macro variables, macro programs (macros) enable you to substitute text into your programs. Macros are different from macro variables because they use conditional logic to make decisions about the text that you substitute into your programs.
You use a macro program you must first define it with a %MACRO statement, then compile it.
General Form:
%MACRO macro_name;
text
%MEND macro_name;
September 17, 2018
05:28

24. SAS Macros General Form:
SAS Programming II
September 17, 2018
SAS Macros
You can also pass in parameters to your macro programs. You would first define and compile it like before.
General Form:
Side note: You will notice that your Results Viewer fills up rather quickly while you are working. If you want to delete everything in there you may find this code helpful.
%MACRO macro_name(parameter1=, parameter2=,..);
text
%MEND;
September 17, 2018
05:28

25. DATA set manipulation
SAS Programming II
September 17, 2018
Loops
In SAS Programming I we learned IF-THEN-ELSE statement syntax which allowed us to execute one statement. Recall…
To execute multiple statements, we can implement a loop using DO and END statements.
General Form:
IF <expression 1> THEN <statement>;
ELSE IF <expression2> THEN <statement2>;
ELSE <statement3>;
IF <expression 1> THEN DO;
<statement>;
END;
ELSE DO;
<statement2>;
September 17, 2018
05:28

26. Macros
SAS Programming II
September 17, 2018
SAS Macros
When you submit SAS programs with macros it goes to macro processor, which generates SAS code from the macro references. SAS then compiles your code and executes your program.
Oddly, not until final execution does SAS finally see any actual data values.
CALL SYMPUT(macro_var_name, value) takes a value from a DATA step and assigns it a macro variable.
Note: You will need to convert numeric to character and trim blanks using this approach.
September 17, 2018
05:28

27. References September 17, 2018 References SAS Programming II