Statistical Analysis System (SAS) Programming Certification Practice Exam

At the start of DATA step processing, observations are set to which of the following?

1. blank

2. missing

3. 0

4. there are no observations

The correct answer is: there are no observations

At the start of a DATA step processing in SAS, there are no observations available to work with. This reflects the foundational principle of how the DATA step operates—initializing a new data structure without any content. Until the DATA step reads data from external sources or generates new data within the program, the data set is essentially empty. The concept of "no observations" indicates that while the structure for the data exists, no rows have been created or loaded into memory yet. Only after executing the INPUT statement or other data-loading commands can the data set begin to accumulate observations. Other choices imply the presence of data in some form, but they do not accurately capture the state at the beginning of processing. Blank, missing, and zero (0) suggest some initialization status that does not appropriately reflect the absence of any observations prior to executing the body of the DATA step.