Base SAS

Question 1

What is the basic structure of the SAS base program?

Answer 1

DATA step, which recovers & manipulates data.

PROC step, which interprets the data.

Question 2

What is the basic syntax style in SAS?

Answer 2

• There should be a semi-colon at the end of every line
• A data statement that defines your data set
• Input statement
• There should be at least one space between each word or statement
• A run statement

Question 3

Explain data step in SAS

Answer 3

The Data step creates a SAS dataset which carries the data along with a “data dictionary.” The data dictionary holds information about the variables and their properties.

Question 4

What are the data types does SAS contain?

Answer 4

The data types in SAS are Numeric and Character.

Question 5

Which statement does not perform automatic conversions in comparisons?

Answer 5

In SAS, the “where” statement does not perform automatic conversions in comparisons.

Question 6

What is a method to debug and test your SAS program?

Answer 6

This combination of options tells SAS to execute the step and analyze the syntax of your code without reading any input data.
options OBS=0 NOREPLACE;

Question 7

What is the difference between nodupkey and nodup options?

Answer 7

The difference between the NODUP and NODUPKEY is that NODUP compares all the variables in our dataset while NODUPKEY compares just the BY variables

Question 8

What does PROC print, and PROC contents do?

Answer 8

To display the contents of the SAS dataset PROC print is used and also to assure that the data were read into SAS correctly. While PROC CONTENTS display information about a SAS dataset.

Question 9

What is the use of function Proc summary?

Answer 9

The syntax of proc summary is the same as that of proc means. It computes descriptive statistics on numeric variables in the SAS dataset.

Question 10

What Proc glm does?

Answer 10

Proc glm performs simple and multiple regression, analysis of variance (ANOVAL), analysis of covariance, multivariate analysis of variance and repeated measure analysis of variance.

Question 11

What is SAS informats?

Answer 11

SAS INFORMATS are used to read, or input data from external files known as Flat Files ASCII files, text files or sequential files). The informat will tell SAS on how to read data into SAS variables.

Question 12

Name types of category in which SAS Informats are placed

Answer 12

Character Informats : $INFORMATw
Numeric Informats : INFORMAT w.d
Date/Time Informats: INFORMAT w.

Question 13

What is the use of PROC gplot?

Answer 13

PROC gplot has more options and can create more colorful and fancier graphics.

Question 14

What is the difference between INPUT and INFILE ?

Answer 14

INFILE statement is used to identify an external file

INPUT statement is used to describe your variables

Question 15

State the difference between INFORMAT and FORMAT ?

Answer 15

INFORMAT: To indicate SAS how to read data into a dataset.
FORMAT: To indicate SAS how to print the variables

Question 16

How you can read the variables that you need?

Answer 16

You read the variables using input statement with column /line pointers, informats and length specifiers.

Question 17

What are the special input delimiters used in SAS?

Answer 17

Special input delimiters used in SAS are DLM and DSD

Question 18

How to include or exclude specific variables in a data set?

Answer 18

To include or exclude specific variables in a data set you can use DROP, KEEP Statements and Data set Options.

Question 19

What is the difference between SAS functions and procedures?

Answer 19

Procedures expect one variable value per observation

Functions expect values to be supplied across an observation

Question 20

What are the default statistics that PROC MEANS produce?

Answer 20

N
MN
MAX
MEAN
STD DEV

Question 21

What is the difference between Match Merge and One to One Merge?

Answer 21

A one-to-one merge is suitable if both data sets in the merge statement are sorted by id, and each observation in one data set has a corresponding observation in the other data set. If the observations do not match, then match merging is suitable.

Question 22

What is the use of the %include statement?

Answer 22

%INCLUDE statement reads an entire file into the current SAS program you are running and submits that file to the SAS System immediately.

Question 23

What does the trace option do?

Answer 23

ODS Trace is used to find the names of the particular output objects when several of them are created by some procedure.

Question 24

How would you identify a macro variable?

Answer 24

with Ampersand (&) sign

Question 25

How would you define the end of a macro?

Answer 25

The end of the macro is defined by %Mend Statement

Question 26

What is the difference between %LOCAL and %GLOBAL?

Answer 26

% Local is a macro variable defined inside a macro. %Global is a macro variable defined in open code (outside the macro or can use anywhere).

Question 27

What do you understand by the term Normal Distribution?

Answer 27

data is distributed around a central value without any bias to the left or right and reaches normal distribution in the form of a bell-shaped curve. The random variables are distributed in the form of a symmetrical bell-shaped curve.

Question 28

What does P-value signify about the statistical data?

Answer 28

P-value is used to determine the significance of results after a hypothesis test in statistics. P-value helps the readers to draw conclusions and is always between 0 and 1. The probability of obtaining test results at least as extreme as the results that are actually observed.

Question 29

Difference between sum function and using “+” operator?

Answer 29

SUM function returns the sum of non-missing arguments. ‘+’ operator returns a missing value if any of the arguments are missing.

Question 30

What is %LET?

Answer 30

%LET is a straightforward macro statement that simply assigns a value to a macro variable.

Question 31

How to begin a macro?

Answer 31

%MACRO

Question 32

What is regression analysis?

Answer 32

Predict a value of the Y variable given known values of the X variable.