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What is computer?

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• A computer is a programmable electronic device that accepts and processes input with a set of instructions and produces the output.

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What is software?

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• Software is a collection of instructions that tell a computer how to work.

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What is SAS?

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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

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What is data?

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• Data refers to the distinct pieces of information, usually formatted and stored in a way to meet a specific purpose.

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What is data entry?

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• Data Entry is the task of entering or updating the data into the computer system by using particular software.

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What is data retrieval?

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• Data retrieval is the process of obtaining data from a Database Management System.

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What is data management?

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• Data management is the process of collection, storage, organization and maintenance of the data

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What is 'Report'?

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• Give a written account of something that one has observed, done, or investigated.

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What is statistics?

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• Statistics is a branch of mathematics dealing with the collection, organization, analysis, interpretation and presentation of data.

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What is Statistical Analysis?

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• It�s the science of collecting, exploring and presenting large amounts of data to discover underlying patterns and trends.

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How do we use SAS?

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• 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:

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• What is the input data?
• What analysis we want to perform?
• How do we want the report to look like?

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What kind of questions can SAS help us answer?

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• 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?

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• 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.

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What is a SAS program?

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• A SAS program is a series of instructions (statements) which communicate what we want SAS to do it.

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What does a SAS program contain?

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• 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'.

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What happens when we execute a SAS program?

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• 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.

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How does SAS expect our data to be organized?

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• 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.

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Dataset structure, variables and observations