What is the impact of using the NODUPKEY option in data processing?

When utilizing the NODUPKEY option during data processing in SAS, it effectively removes duplicate observations from a dataset based on specified key variables. This option operates in conjunction with sorting the data, ensuring that duplicates are identified correctly based on the key variables.

The primary function of NODUPKEY is to keep only the first occurrence of each unique value in the specified key fields. This means that once the data is sorted, the option will scan through the dataset and retain just the first record it encounters for any duplicate key values, discarding any additional records that match those key values.

The combined effect of these operations explains why the choice that encompasses all aspects—eliminating duplicate records, sorting the data by key variables, and retaining only the first occurrence of a duplicate—is accurate. It indicates that the option is a comprehensive solution for managing duplicates while keeping the data organized according to the sorting criteria.