What you will learn
- Reconstruct an as-of dataset
- Track vendor corrections
- Reconcile overlapping feeds
- Document licensing and retention constraints
Reconstruct an as-of dataset
An as-of dataset contains only information available by a specified decision time. Observation dates alone are insufficient for revised economic data or corrected market records. Record publication and revision timing.
Track vendor corrections
Vendor corrections should be versioned so a study can distinguish original observations from later cleaned data. Both can be useful for different questions, but they should not be silently interchanged.
Reconcile overlapping feeds
Reconcile overlapping feeds with explicit priority and conflict rules. A merge that chooses the best-looking price after seeing outcomes can create artificial performance. Preserve source attribution for each retained observation.
Document licensing and retention constraints
Licensing, access and retention terms constrain how data can be used and shared. A reproducibility package may need hashes, schemas and retrieval instructions rather than redistribution of restricted raw files.
Worked example
A monthly observation released on the tenth is stored with the first day of the month. Joining on observation date would let a strategy use it nine days before publication.
Try it yourself
Define an as-of join that avoids this error and explain how later revisions should be represented.
Show the worked solution
Join on availability time at or before the decision, retaining the original observation period. Store later revisions as separate versions with their own availability times so historical information sets can be reconstructed.
Apply this to your course project
Deliver a versioned dataset and a quality report.
Keep the calculation inputs, assumptions and decisions with your work. Practical exercises are self-reviewed; the scored knowledge checks assess the questions shown, not an independent certification of practical competence.