ORIGINAL COMPANY-CONTEXT PRACTICE
Compare sales when package sizes change
Original practice scenario: A hypothetical warehouse-retail report compares product sales before and after a pack changes from twelve units to ten. The SKU identifier is reused. Design the comparison.
Written for independent practice using company context; this is not a verified question from a company interview.
A REASONED APPROACH
Model answer.
Keep package sales and underlying units separate, with an effective-dated product specification. Equal SKU counts do not imply equal quantities when the contents of each package change.
Work through it
- Store sale lines at transaction-line grain and join the product specification valid at the sale time, detecting gaps or overlapping specification intervals.
- Calculate package count, underlying-unit count and monetary totals separately, preserving returns and any non-equivalent units of measure.
- Compare periods using explicit price and promotion context, reconciling totals back to source lines and identifying stock sold under an older packaging version.
Tradeoffs to discuss
- Standardized-unit comparisons improve continuity but can obscure customer-facing packaging differences; both views may be useful.
Common pitfalls
- Joining every specification version to one sale multiplies its contribution.
- Do not infer the package version solely from today's catalog when older stock may still be sold.