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What is a computer
- A computer is a programmable electronic device that accepts input, processes instructions, and produces output
What is software
- Software is a collection of instructions that tells a computer how to work
What is SAS
- SAS is an integrated system of software solutions used for data entry, retrieval, management, reporting, and statistical analysis
- It can be used to manage data, create reports, perform descriptive analysis, and carry out more advanced statistical procedures
What is data
- Data refers to distinct pieces of information collected and stored for a purpose
What is data entry
- Data entry is the task of entering or updating data in a computer system
What is data retrieval
- Data retrieval is the process of obtaining stored data for use or review
What is data management
- Data management is the collection, storage, organisation, and maintenance of data
What is a report
- A report is a structured presentation of information, observations, or findings
What is statistics
- Statistics is the branch of mathematics concerned with collecting, organising, analysing, interpreting, and presenting data
What is statistical analysis
- Statistical analysis is the process of exploring and summarising data to understand patterns, relationships, and differences
How do we use SAS
- We provide instructions to SAS through SAS programs
- Those instructions tell SAS what the input data is, what analysis to perform, and what kind of result or report is needed
What kind of questions can SAS help us answer
- Class example: average height, weight, and age of students in a class
- Class example: number of males and females in a class
- Cars example: average, minimum, and maximum mileage for each car maker
- Cars example: number of models available from each car maker
- Clinical trial example: total number of subjects in a study
- Clinical trial example: number of subjects in each treatment group
- Clinical trial example: number of males and females within each treatment group
How do we provide instructions to SAS
- SAS includes its own programming language called SAS language
- We provide instructions to SAS in the form of a SAS program written in that language
What is a SAS program
- A SAS program is a series of statements that tells SAS what to do
What does a SAS program contain
- A SAS program contains one or more instruction sets called steps
- SAS executes one step at a time
- These steps are broadly classified into DATA steps and PROC steps
What happens when we execute a SAS program
- SAS checks whether it understands the submitted instructions
- If serious issues are found, execution may stop
- Otherwise, SAS completes the requested processing and produces results or output datasets
How does SAS expect data to be organised
- SAS expects data to be in tabular form with rows representing observations and columns representing variables
- An observation contains the collection of values for one entity such as one student, one car, or one subject
- A variable contains the same type of information across observations such as age, sex, or weight
Dataset structure, variables, and observations
Create a simple example dataset
- This small example illustrates how rows and columns appear in a SAS dataset
- Review the output dataset and identify the observations and variables
- Each row of `class_demo` is one observation
- Each column such as `name`, `sex`, `age`, `height`, and `weight` is a variable