Explain what is SAS? What are the functions does it performs?
SAS means Statistical Analysis System, which is an integrated set of software products.
- Information retrieval and data management
- Writing reports and graphics
- Statistical analysis, econometrics and data mining
- Business planning, forecasting and decision support
- Operation research andProject management
- Quality Improvement
- Data Warehousing
- Application Development
Explain what is the basic structure of SAS programing?
The basic structure of SAS are
- Program Editor
- Explorer Window
- Log Window
What is the basic syntax style in SAS?
To run program successfully, and you have following basic elements:
- 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
For example: Infile ‘H: StatHWyourfilename.dat’;
Explain what is Data Step?
The Data step creates an SAS dataset which carries the data along with a “data dictionary.” The data dictionary holds the information about the variables and their properties.
Explain what is PDV?
The logical area in the memory is represented by PDV or Program Data Vector. At the time, SAS creates a database of one observation at a time. An input buffer is created at the time of compilation which holds a record from an external file. The PDV is created following the input buffer creation
Mention what are the data types does SAS contain?
The data types in SAS are Numeric and Character.
In SAS explain which statement does not perform automatic conversions in comparisons?
In SAS, the “where” statement does not perform automatic conversions in comparisons.
Explain how you can debug and test your SAS program?
You can debug and test your SAS program by using Obs=0 and systems options to trace the program execution in log
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Mention what is the difference between nodupkey and nodup options?
The difference between the NODUP and NODUPKEY is that, NODUP compares all the variables in our dataset while NODUPKEY compares just the BY variables
Mention the validation tools used in SAS?
For DataSet : Data set name/ debug Data set: Name/stmtchk
For Macros: Options: mprint mlogic symbolgen
Explain what does PROC print, and PROC contents are used for?
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 an SAS dataset.
Explain what is the use of function Proc summary?
The syntax of proc summary is same as that of proc means, it computes descriptive statistics on numeric variables in the SAS dataset.
Explain what Proc glm does?
Proc glm performs simple and multiple regression, analysis of variance (ANOVAL), analysis of covariance, multivariate analysis of variance and repeated measure analysis of variance.
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Explain what is SAS informats?
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.
Mention the category in which SAS Informats are placed?
SAS informats are placed in three categories,
• Character Informats : $INFORMATw
• Numeric Informats : INFORMAT w.d
• Date/Time Informats: INFORMAT w.
What function CATX syntax does?
CATX syntax concatenate character strings remove trailing and leading blanks and inserts separators.
Explain what is the use of PROC gplot?
PROC gplot has more options and can create more colorful and fancier graphics.
It performs simple and multiple regression, analysis of variance (ANOVAL), analysis of covariance, multivariate analysis of variance and repeated measure analysis of variance.
What is difference between CEIL and FLOOR functions?
The cell function returns the smallest integer greater than/equal to the argument whereas the floor returns the greatest integer less than/equal to the argument.
How debug SAS Macros?
There are some system options that can be used to debug SAS Macros: MPRINT, MLOGIC, SYMBOLGEN
How to save log in an external file?
Use PROC PRINTTO
What is the difference between SAS PROCs and the SAS DATA STEP?
Procs are sub-routines with a specific purpose in mind and the data step is designed to read in and manipulate data.
How can you write a SAS data set to a comma delimited file?
PUT (formatted) statement in data step.
Difference between Input and Put function?
Input function – Character to numeric conversion- Input (source, Informat) and put function – Numeric to character conversion- put (source, format)
BY processing requires that your data already be sorted or indexed in the order of the BY variables.
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