Final answer:
The correct statement about match-merging is that when using the MERGE statement with a BY statement, the data must be sorted or indexed on the BY variable.
Step-by-step explanation:
Regarding match-merging in data processing, let's address each statement provided:
- a. The MERGE statement must refer to permanent data sets. - This is not necessarily true, as the MERGE statement can work with temporary data sets as well as permanent ones.
- b. The variables in the BY statement can be in only one of the data sets. - This is incorrect; the variables specified in the BY statement must be present in all the data sets being merged to serve as a key for the merging process.
- c. Only two data sets can be specified in the MERGE statement. - This is also not true; SAS allows for multiple data sets to be merged in a single MERGE statement.
- d. When you use the MERGE statement with the BY statement, the data must be sorted or indexed on the BY variable - This is the correct statement. For a successful match-merge, the data in each dataset must be sorted or indexed by the variables specified in the BY statement.
The correct answer is d. When performing a match-merge, the datasets to be merged should be sorted or indexed on the BY variables to correctly align the data rows based on the keys defined by these variables.