Introduction to SAS
At the heart of SAS is a programming language made up of statements that specify how data are to be processed and analysed. The statements correspond to operations to be performed on the data or instructions about the analysis. A SAS program consists of a sequence of SAS statements grouped together into blocks, referred to as ‘‘steps’’. These fall into two types: data steps and procedure (proc) steps. A data step is used to prepare data for analysis. It creates a SAS data set and may re-organize the data and modify it in the process. A proc step is used to perform a particular type of analysis, or statistical test, on the data in a SAS data set.