Tag Archives: sas datasets

SAS Proficiency Test

Here are some common SAS questions:

1- What happens if no VAR statement is used in PROC PRINT?

2- Understand how SAS processes a data step

3- Explain what a (data step) SELECT statement does

4- What is the default length of a numeric variable?

5-What is the difference between DO WHILE and DO UNTIL?

6-What does BY after SET A; do?

7-What does BY after SET A B; do?

8-What is a sub-setting IF statement?

If you pass it doesn’t mean you’re good; but if you’re good, you should pass

9- What’s the difference between INFILE and INPUT?

10-What information is given by a Proc Contents?

11-How do you modify the header?

12-Which elements can you change? (in reference to question 10-11)

13-Which elements can you NOT change without re-creating the dataset?(in reference to question 10-11)

14-What is the purpose of the single trailing @ sign?

15-What statements are used to include or exclude specific variables in a data step?

16-How can you generate a 2-dimensional cross-tabulation?

17-In the macro language, all macro commands begin with?

18-What occurs if multiple datasets are included in a SET statement?

19-What symbol is used to concatenate two character values?

20-Explain the substr function

21-What are the differences among these functions? Round(), Ceil(), Floor()

22-What happens if you use the same in= variable for 2 datasets?

23-How do you begin a data step if you do not want to create a SAS dataset?

24-What are the automatic variables first. and last. ?

25-What does a 2 level input dataset name such as MydataSet.Mydata indicate ?

26-What is the default libname, where one-level dataset names go?

27-What statement allows you to keep track of previous values of variables or keep a running total?

28-What happens if you retain the value of a variable in the incoming dataset?

29-When an invalid data field is encountered when inputting a numeric variable, what happens?

30-What’s the difference between $w. and $CHARw. informats?

31-Explain the _type_ variable generated by proc summary

32-What is the purpose of a %GLOBAL statement?

33-What do CALL SYMPUT and CALL SYMGET do?

34-What date is the reference date for calculating the value of a SAS date variable?

35-What is _n_?

There are 10 kinds of people in the world: those who understand binary, and those who don’t.

Those are SAS most common questions you will be asked during a SAS programming job interview or if you plan in taking the SAS based certification.

In future blogs, I will try to cover each of those questions individually with some demonstrations.

Good luck!

Your comments and questions are valued and encouraged.
Anayansi Gamboa has an extensive background in clinical data management as well as experience with different EDC systems including Oracle InForm, InForm Architect, Central Designer, CIS, Clintrial, Medidata Rave, Central Coding, OpenClinica, Open Source and Oracle Clinical.

 

anayansi gamboa

Advertisements

How to Use SAS – Lesson 2 – Creating Datasets on the Fly

This video series is intended to help you learn how to program using SAS for your statistical needs. Lesson 2 introduces some basic data step programming to define variables and specify their values for data sets containing one or more observations.

I also introduce two procedures: the PRINT procedure (PROC ;PRINT) to display the data contents in the OUTPUT window, and the CONTENTS procedure (PROC CONTENTS) to summarize the data set. Finally, I introduce the concept of libraries to show another method of inspecting the data set by physically opening it from the temporary WORK library.

Helpful Notes:

1. PROC PRINT – displays the entire data set by observation in the OUTPUT window
2. PROC CONTENTS – summarizes the properties of a data set, including an alphabetic listing of the variables and a count of the number of observations.
3. The assignment operator (“=”) directly specifies the value of a variable in the data step.
4. The INPUT statement defines one or more variables of our data set.
5. The CARDS statement specifies the values for each of the INPUT variables (in order).
6. It is a good rule of thumb to always pair the INPUT and CARDS statements together.
7. DON’T FORGET SEMI;COLONS! They end statements and without them, you will most certainly have errors arise.
8. If you have any errors, always, ALWAYS, ALWAYS check the LOG first!
9. Creating datasets “on-the-fly” just means you’re making a new dataset without bringing in the data from any other source.

Today’s Code:

data main;
input x y z;
cards;
1 2 3
7 8 9
;
run;

proc print data=main;
run;

proc contents data=main;
run;

-FAIR ;USE-
“Copyright Disclaimer Under Section 107 of the Copyright Act 1976, allowance is made for “fair use” for purposes such as criticism, comment, news reporting, teaching, scholarship, and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favor of fair use.”

Anayansi Gamboa has an extensive background in clinical data management as well as experience with different EDC systems including Oracle InForm, InForm Architect, Central Designer, CIS, Clintrial, Medidata Rave, Central Coding, OpenClinica Open Source and Oracle Clinical.