SAS (Statistical Analysis System) is a software suite developed by SAS Institute for advanced analytics, business intelligence, data               management, and predictive analytics. It is the largest market-share holder for advanced analytics. SAS was developed at North Carolina State University from 1966 until 1976, when SAS Institute was incorporated. SAS was further developed in the 1980s and 1990s with the addition of new statistical procedures, additional components and the introduction of JMP. A point-and-click interface was added in version 9 in 2004. A social media analytics product was added in 2010.
2. Â What are the special input delimiters?
The input delimiters are DLM and DSD.
3. Â What is the difference between a format and an informat?
Format: A format is to write data i.e. Â WORDIATE18 and WEEKDATEW
Informat: An informat is to read data i.e. comma, dollar and date (MMDDYYw, DATEw, TIMEw, PERCENTw)
4. Â Describe any one SAS function?
RIM: removes trailing blanks from a character expression
Result = TRIM (Str1)(Str2);
5. Â What is Program Data Vector (PDV) and what are its functions ?
PDV is a logical area in the memory
SAS creates a dataset one observation at a time
Input buffer is created at the time of compilation, for holding a record from external file
PDV is created followed by the creation of input buffer
SAS builds dataset in the PDV area of memory
6. Â Compare SAS STATA & SPSS?
Each package offers its own unique strengths and weaknesses. Â As a whole, SAS, Stata and SPSS form a set of tools that can be used for a wide variety of statistical analysis. Â With Stat/Transfer it is very easy to convert data files from one package to another in just a matter of seconds or minutes. Â Therefore, there can be quite an advantage to switching from one analysis package to another depending on the nature of your problem. Â For example, if you were performing analysis using mixed models you might choose SAS, but if you were doing logistic regression you might choose Stata, and if you were doing analysis of variance you might choose SPSS. If you are frequently performing statistical analysis, we would strongly urge you to consider making each one of these packages part of your toolkit for data analysis.
7. Â What are the uses of SAS?
SAS/ETS software provides tools for a wide variety of applications in business, government, and academia. Major uses of SAS/ETS procedures are economic analysis, forecasting, economic and financial modeling, time series analysis, financial reporting, and manipulation of time series data.
The common theme relating the many applications of the software is time series data: SAS/ETS software is useful whenever it is necessary to analyze or predict processes that take place over time or to analyze models that involve simultaneous relationships.
Although SAS/ETS software is most closely associated with business, finance and economics, time series data also arise in many other fields. SAS/ETS software is useful whenever time dependencies, simultaneous relationships, or dynamic processes complicate data analysis.For example, an environmental quality study might use SAS/ETS softwareâs time series analysis tools to analyze pollution emissions data. A pharmacokinetic study might use SAS/ETS softwareâs features for nonlinear systems to model the dynamics of drug metabolism in different tissues.
8. Â What are the features of SAS?
SAS provides a powerful programming language with components called procedures that allow you to perform many different kinds of analysis and data management functions, as well as produce many different types of text-based and graphical presentation output.Combined with other features, the SAS language and its procedures make an immense variety of applications possible, including the following examples:
    Access raw data files and data in external databases and database management systems.
    Manage data using tools for data entry, editing, retrieval, formatting, and conversion.
    Analyze data using descriptive statistics, multivariate techniques, forecasting and modeling, and linear programming.
    Present data using reports and business and statistical graphics.
SAS is also portable across computing environments. SAS applications function the same and produce the same results regardless of the operating environment on which you are running SAS to process your data. However, some features, such as interactive windows, are not supported on all platforms.
9. Â How do I Create a SAS Data Set with Compressed Observations?
To create a compressed SAS data set, use the COMPRESS=YES option as an output DATA set option or in an OPTIONS Â Â statement.Compressing a data set reduces its size by reducing repeated consecutive characters or numbers to 2-bye or 3-byte representations.To uncompress observations, you must use a DATA step to copy the data set and use option COMPRESS=NO for the new data set.
The advantages of using a SAS compressed data set are reduced storage requirements for the data set and fewer input/output operations necessary to read from and write to the data set during processing. The disadvantages include not being able to use SAS observation number to access an observation. The CPU time required to prepare compressed observations for input/output observations is increased because of the overhead of compressing and expanding the observations. (Note: If there are few repeated characters, a data set can occupy more space       in compressed form than in uncompressed form, due to the higher overhead per observation.) For more details on SAS compression see âSAS Language: Reference, Version 6, First Edition, Cary, NC: SAS Institute Inc., 1990â.
10. Â How can we minimize space requirement for the huge data set in SAS for window?
When you are working with large data sets, you can do the following steps to reduce space requirements.
Split huge data set into smaller data sets.
Clean up your working space as much as possible at each step.
Use data set options (keep= , drop=) or statement (keep, drop) to limit to only the variables needed.
Use IF statement or OBS = to limit the number of observations.
Use WHERE= or WHERE or index to optimize the WHERE expression to limit the number of observations in a Proc Step and Data Step.
Use length to limit the bytes of variables.
Use _null_ data set name when you donât need to create a data set.
Compress data set using system options or data set options (COMPRESS=yes or COMPRESS=binary).
Use SQL to do merge, summary, sort etc. rather than a combination of Proc Step and Data Step with temporary data sets.