A computer is a programmable electronic device that accepts and processes input with a set of instructions and produces the output.
What is software?
Software is a collection of instructions that tell a computer how to work.
What is SAS?
SAS is an integrated system of software solutions that enables us to perform the following tasks:
data entry, retrieval, and management
report writing and graphics design
statistical and mathematical analysis
What is data?
Data refers to the distinct pieces of information, usually formatted and stored in a way to meet a specific purpose.
What is data entry?
Data Entry is the task of entering or updating the data into the computer system by using particular software.
What is data retrieval?
Data retrieval is the process of obtaining data from a Database Management System.
What is data management?
Data management is the process of collection, storage, organization and maintenance of the data
What is 'Report'?
Give a written account of something that one has observed, done, or investigated.
What is statistics?
Statistics is a branch of mathematics dealing with the collection, organization, analysis, interpretation and presentation of data.
What is Statistical Analysis?
It’s the science of collecting, exploring and presenting large amounts of data to discover underlying patterns and trends.
How do we use SAS?
We know that SAS is a 'statistical' software. We also know that SAS is equipped with tools to perform statistical and mathematical analysis. When we have a specific statistical or mathematical question to address, we provide instructions to SAS to get the answer:
What is the input data?
What analysis we want to perform?
How do we want the report to look like?
What kind of questions can SAS help us answer?
Class example
Report the average height, weight and age of all students in a class
Report the number of males and females in class
Report if there is a statistically significant difference in the proportion of males and females in a class
Cars example
Report the average, minimum and maximum mileage of each car maker
Report the number of models available from each car maker
Report if there is a statistically significant difference in the average mileage of Sedan cars produced across different continents
Clinical trial example
Report the total number of volunteers (subjects) participated in a clinical trial
Report the total number of treatments tested in a clinical trial
Report the total number of subjects within each treatment group
Report the number of subjects with age collected, number of subjects with age not collected, average, minimum and maximum age within each treatment group
Report the number of males and females within each treatment group
Report if there is a statistically significant difference in the proportion of males and females between different treatment groups
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How do we provide instructions to SAS?
SAS is equipped with a programming language and is called SAS language. We provide instructions to SAS in SAS language in the form of a sas program.
What is a SAS program?
A SAS program is a series of instructions (statements) which communicate what we want SAS to do it.
What does a SAS program contain?
A SAS program contains a series of 'instruction sets'.
SAS executes one 'instruction set' at a time.
Each instruction set consists of one or more statements.
SAS reads each statement of an instruction set, interprets it and then executes the 'instruction set' as a whole.
Instruction sets can be broadly classified into two types. 1) 'data step' 2) 'proc step'.
What happens when we execute a SAS program?
SAS first checks if the instructions we provided are correct (checks if it actually understands what is requested).
If it encounters any serious issues the execution stops, otherwise it completes the execution and provides the results.
How does SAS expect our data to be organized?
SAS expects the data to be in a tabular format, with rows representing observations and columns representing variables.
That is, a row or an observation represents the collective information about an entity, whereas a column or variable represents the same type of information about different entities on corresponding rows.
