Question

If you process a BY group that consists of a single observation, what are the correct values of FIRST.BY-variable and LAST.BY-variable?

a. FIRST.BY-variable=0 LAST.BY-variable=0
b. FIRST.BY-variable=1 LAST.BY-variable=0
c. FIRST.BY-variable=1 LAST.BY-variable=1
d. FIRST.BY-variable=0 LAST.BY-variable=1

Answer 1

In SAS, for a BY group with a single observation, both FIRST.BY-variable and LAST.BY-variable should be set to 1, indicating that the single observation is the first and last in the group.

Step-by-step explanation:

When you process a BY group in SAS that consists of a single observation, the correct values for the FIRST.BY-variable and LAST.BY-variable are both 1. This is because the single observation is the first and last (and only) occurrence of that BY group. In SAS, FIRST.variable and LAST.variable are temporary variables created during the DATA step that indicate whether the current observation is the first or last observation in each BY group.

So for a BY group with a single observation:

• FIRST.BY-variable = 1 (it is the first observation in the BY group)
• LAST.BY-variable = 1 (it is also the last observation in the BY group)