Here are the Top 50 Important SAS Programmer Interview Questions and Answers that you should not miss before your interview
1. What is SAS?
SAS (Statistical Analytics System) is one of the leading analytics software tools. SAS Institute has developed it. It allows the programmer to alter, manage and retrieve various kinds of data sets from various different sources and perform statistical analysis on that collected data
2. Can you list the functions performed by SAS?
Yes, absolutely, so the functions performed by SAS software are:
- Data Management
- Data Extraction
- Data Transformation
- Statistical Analysis
- Business Modeling
- Application Development
- Report Writing
- Quality Improvement
3. Name the three components in SAS programming.
The three components of SAS are:
- Statements
- Variables
- Datasets
4. What is the SAS Dataset?
A SAS Data Set is the data set present for analysis within a SAS application. It is also known as a SAS data table. It consists of two parts, Columns of variables and Rows of Observation.
5. What are the benefits of SAS?
There are various benefits of SAS, such as;
- SAS Syntax is easy to learn.
- It only takes a 2 to 3-month training course to learn SAS
- It can handle a large database.
- SAS is a closed-source language that comes with thorough test algorithms.
- It is easy to debug as it is a comprehensible language.
- SAS has a great Graphical User Interface (GUI) that has various tools like graphs, plots, and a highly versatile library.
- It is in huge demand in the market and offers great corporate jobs with better growth opportunities and a stable career.
6. Are you aware of all the features of SAS?
Yes! I am aware of all the features of SAS. They are:
- Strong Data Analysis Abilities
- Flexible 4 Generation Programming Language (4GL)
- Management
- SAS Studio
- Support for Various Types of Data Format
- Data Encryption Algorithm
- Report Output Format
7. List some capabilities of the SAS Framework.
Some capabilities of the SAS Framework are:
- Access
- Manage
- Analyze
- Present
8. Explain the basic structure of the SAS base program.
The basic structure of SAS consists of:
- ‘==DATA’ step, which recovers & manipulates data.
- ‘==PROC’ step, which interprets the data.
9. Explain the uses of the TRANWRD function.
The TRANWRD function manages the functionality for search and replacement. It is used to remove and replace all instances of given words. It does not remove trailing blankets in the replacement string and the target string.
10. Why is double trailing @@ used in input statements?
Double trailing @@ because it indicates that SAS should hold the current record to execute the next Input statement. Rather than moving to the new record during data step iteration.
11. What are the methods to perform a “table lookup” in SAS?
There are five methods to perform “table lookup” in SAS:
- Match Merging
- Format Tables
- Direct Access
- PROC SQL
- Arrays
12. Do you know the different ways of creating micro variables in SAS programming?
Yes, I am aware that 5 different ways of creating micro variables are:
- %Global
- Macro parameters
- %Let
- Call Symput
- Proc SQL into clause
13. Write the default statistics that PROC MEANS produces.
Below are the default statistics PROC MEANS produces:
- N
- MN
- MAX
- MEAN
- STD DEV
14. Can you tell us what the most common programming errors that occur in SAS are?
The most common programming errors in SAS are:
- Missing a semicolon
- Unmatched quotation marks
- Invalid dataset option
- Invalid statement option
- Not using debugging techniques
- Not checking the log after submitting the program
- Not using the FSVIEW option vigorously
15. Do you know at what length the Scan function gives the target variable?
The SCAN function is used to return a specified word from a character string, using either default or specific delimiters. The length allotted to the target variable by the scan function is 200.
16. Difference between INPUT and INFILE
The INFILE statement is used to identify an external file while the INPUT statement is used to describe your variables.
FILENAME TEST ‘C:\DEEP\File1.xls’;
DATA READIN;
INFILE TEST;
LENGTH NAME $25;
INPUT ID NAME$ SEX;
RUN;
17. What is the difference between DO WHILE and DO UNTIL?
The DO WHILE expression is evaluated at the top of the DO loop. If the expression is false the first time it is evaluated, then the DO loop will not execute even once. On the other hand, DO UNTIL executes at least once.
18. Tell us how to print observations 5 through 10 from a data set?
The FIRSTOBS= and OBS=data set options would tell SAS to print observations 5 through 10 from the data set READIN.
19. Do you know what is the basic syntax style in SAS?
Yes, SAS programs consist of three main components:
- DATA steps to manage and manipulate data.
- PROC steps to analyse data using procedures.
- Statements that end with a semicolon (;).
20. Tell us what the default statistics are produced by PROC MEANS?
The “default” statistics of N, MIN, MAX, MEAN and STD DEV are produced by PROC MEANS.
21. Write code using PROC SORT on a data set containing State, District, and County as the primary variables, along with several numeric variables.
Ans. Syntax:
Proc sort data= Dist_County;
By state district city;
Run;
22. Can you tell us how to remove duplicates using PROC SQL?
Ans. Sure, Duplicates can be removed by:
Proc SQL noprint;
Create Table inter.Merged1 as
Select distinct * from inter.readin ;
Quit;
23. What is the difference between a SAS program and a SAS macro?
A set of SAS statements that process data is called a SAS program. A stored set of SAS statements that can be called and executed multiple times within a program is considered a SAS macro
24. What is a SAS Data Step?
A SAS data step is needed to read and modify data. SAS data steps can also create SAS datasets by processing raw data, datasets, or other data sources.
25. What is the difference between Missover and Truncover?
Missover – When the Missover option is specified in the INFILE statement, the INPUT statement does not move to the next line if the current line is shorter than expected. Instead, any variables that do not receive values are automatically assigned missing values.
Truncover – The Truncover option assigns whatever data is available in the record to the variable, even if the value is shorter than what the INPUT statement expects. Unlike Missover, which simply sets missing values when data runs out, Truncover captures the partial value for the variable at the end of the record.
Key Difference – Missover leaves variables without enough data as missing, while Truncover uses any partial data available at the end of the record to fill the variable.
26. Tell us how to include or exclude specific variables in a data set?
Ans. We use DROP, KEEP statements and dataset options to include or exclude specific variables in a data set
DROP Statement:
It states SAS the names of the variables to be removed from the data set.
For example, the following code will drop the variable score from the data set:
data readin1;
set readin;
drop score;
run;
KEEP Statement:
It specifies the names of the variables to be retained from the data set.
For example, the following code will keep the variable sum in the data set:
data readin1;
set readin;
keep sum;
run;
DROP, KEEP Data set Options:
The DROP= KEEP= data set option differs from the DROP KEEP statement as the DROP KEEP statement cannot be used in procedures.
For example:
data readin1 (drop=score);
set readin;
run;
data readin1 (keep=sum);
set readin;
run;
27. Are you aware of the PROC step in SAS?
Yes, I am aware of the PROC step in SAS. A PROC step is a procedure used to perform specific operations on datasets, like sorting, summarising, or creating statistical analysis reports.
28. Can you tell us what the different types of variables in SAS?
Sure, there are two types of variables in SAS:
- Numeric: This represents numbers and allows mathematical calculations.
- Character: This represents text or strings.
29. Tell us how you will create a new SAS dataset?
To create a new SAS dataset, I’ll use the DATA step or I can import data from an external source using PROC IMPORT
30. What is a SAS library?
A SAS library is a directory that stores SAS datasets. Each library is assigned a libref, a name that SAS uses to identify the directory.
31. What is the purpose of the WHERE statement?
The WHERE statement is used to subset data based on specified conditions, allowing you to filter observations in a dataset.
32. What is the difference between LENGTH and FORMAT statements?
LENGTH is used to specify the number of bytes used to store a variable,
FORMAT is used to specify how the variable should be displayed or printed.
33. What is the difference between the PROC SORT and the BY statement?
PROC SORT is used to sort a dataset.
BY statement is used to process data that is already sorted by specified variables.
34. Do you know what the difference is between FORMAT and INFORMAT in SAS?
- FORMAT: Displays data in a particular way.
- INFORMAT: Reads data in a specific format during the data input phase.
35. Tell us about the advantages of using SAS?
Some advantages of SAS include:
- Powerful data manipulation capabilities.
- Advanced analytics and statistical functions.
- Good integration with databases and other software.
- Comprehensive support for data handling and reporting.
36. How do you concatenate two strings in SAS?
You can concatenate strings using the double pipe operator (||) or the CAT function.
37. How to use arrays to recode all the numeric variables?
Ans. We can use _numeric_ and dim functions in the array to recode all the numeric variables.
data readin;
set outdata;
array Q(*) _numeric_;
do i=1 to dim(Q);
if Q(i)=6 then Q(i)=.;
end;
run;
38. Explain the difference between the SAS sum function and using the “+” operator.
Ans. In SAS, the sum function returns the sum of missing and non-missing arguments, whereas the “+” operator returns a missing value if any argument or value is missing.
Example:
data mydata;
input x y z;
cards;
33 3 3
24 3 4
24 3 4
. 3 2
23 . 3
54 4.
35 4 2
;
run;
data mydata2;
set mydata;
a=sum(x,y,z);
p=x+y+z;
Run;
In this code, the value of p is missing from the 4th, 5th, and 6th observation
Output:
a p
39 39
31 31
31 31
5.
26.
58.
41 41
39. What does the P-value signify about the statistical data?
In statistics, the P-value helps evaluate the result of a test and always ranges between 0 and 1. It provides an easy way to draw conclusions about the null hypothesis:
- If P-value > 0.05, it suggests weak evidence against the null hypothesis, so the null hypothesis is not rejected.
- If P-value ≤ 0.05, it indicates strong evidence against the null hypothesis, allowing us to reject it.
- If P-value = 0.05, it is considered a borderline or marginal case, where the decision could reasonably go either way.
40. How to create Macro variables in SAS programming?
Ans. There are many different ways to create macro variables in SAS programming, such as:
- CALL SYMPUTX routin
- %LET statement
- Macro parameters
- INTO in PROC SQL
- %DO statement (iterative)
41. Tell us what the CALL MISSING Routine mean to you?
The CALL MISSING procedure is used to assign missing values to the numeric variables or the given character
42. What is PDV (Program Data Vector)?
A Program Data Vector (PDV) is a logical area of memory in SAS where datasets are built, one observation at a time. When a program runs, SAS either reads data values from the input buffer or generates them through SAS language statements, then assigns these values to the corresponding variables in the PDV.
In addition to user-defined variables, the PDV also contains two automatic variables:
- N – represents the number of times the DATA step has iterated.
- ERROR – indicates whether an error has occurred during data reading (0 = no error, 1 = error).
43. Describe the purpose of VFORMATX.
The VFORMATX function is used to return the format associated with the value of a given statement
44. What use does $BASE64X serve?
$BASE64X is used to encode into ASCII text
45. What is the STD function?
The STD function is used to return the standard deviation for the non-missing statements
46. What distinguishes the NODUPKEY and NODUP choices?
NODUP: Verifies and eliminates duplicate observations.
NODUPKEY: searches for all BY variable values and, if any are found, eliminates them.
47. Which SAS command does not automatically convert values while doing comparisons?
Automatic conversions are not possible with WHERE statements since the data set contains WHERE statement variables.
48. How should the SAS software be validated properly?
The OPTIONS OBS=0; statement should be placed at the beginning of the code. When executed, the program will not process any observations, but a log will still be generated, which can be identified through the highlighted colours in the log window.
49. Can you explain to us some SAS character functions that are used for data cleaning in brief?
Ans. Sure, the SAS character functions that are used for data cleaning in brief:
- LOWCASE(char_string) Function: It converts all the characters in a given string to lowercase.
- UPCASE(char_string) Function: This converts all the characters in a given string to uppercase.
- COMPBL(str) Function: It compresses multiple blanks to a single blank.
- TRIM(str) Function: It removes trailing blanks from a given string.
- Strip Function: It removes leading and trailing spaces.
- Compress(char_string) Function: It removes leading, between, and trailing spaces.
- Find Function: It is used to locate a substring within a string
50. Can you explain to us the conditions under which you code a SELECT construct instead of IF statements?
Ans. When you have numeric values and a long series of exclusive conditions, then using the SELECT group rather than IF-THEN or IF-THEN-ELSE statements is better. It also reduces CPU time.
The syntax for SELECT WHEN is as follows:
SELECT (condition);
WHEN (1) x=x;
WHEN (2) x=x*2;
OTHERWISE x=x-1;
END;
Example :
SELECT (str);
WHEN (‘Sun’) wage=wage*1.5;
WHEN (‘Sat’) wage=wage*1.3;
OTHERWISE DO;
wage=wage+1;
bonus=0;
END;
END;
