Data Management and Manipulation
One-to-One Merge
A one-to-one merge is appropriate only when the merge key identifies one row in each dataset.
Page 1 of 7 · Big Picture
The big picture: One-to-One Merge
When does each key identify exactly one row in both files?
Why a policy analyst should care
A one-to-one merge is valid only when each key identifies one record in each file; unnoticed duplicates can silently multiply observations and corrupt results.
Follow the idea from the opening question to a practical decision. These are the conceptual moves this module will develop:
1 Question When is a key unique in both files?
2 Explore A person-year example
3 Formalize Validate uniqueness before merging
4 Transfer Audit a one-to-one merge
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