including data entry and manipulation and simple statistical operations. Purchasers of SAS can the decide what additional modules they SAS/IML module (Interactive Matrix Language). And the SAS/STAT module for more advanced statistical operations. There is also a directly, in a similar manner as to many other statistical software packages. It does not, however, use Microsoft Windows dialogue boxes that users might expect, and it is much less user friendly than other packages in this regard. Unless SAS/ASSIST or some other interactive system is being used, the user writing a program and then submitting it to the system operates the package. The system then processes the statements and produces output, as appropriate, and a log file, giving details of what operations were carried out. So why does SAS not have a user-friendly interface? Why does it expect its users to team how to write programs? The answers lie in the nature of research project: they are typically undertaken by a group of researchers and are ongoing for a signification amount of time. This means that a record must be kept of exactly what data manipulations, analyses etc, were accomplished. Keeping programs of statements, which can contain comments on what the programs do, what revisions were made, dates on which the programs were created, and when revisions were made, is an effective tool. These programs can also contain statements that carry out many analyses and data manipulations within the same program. When revisions are made to these more complex programs.