Why this is mistaken
These labels summarize response direction under a defined relationship. Positive income response supports “normal”; negative supports “inferior.” Positive cross-price response supports “substitute”; negative supports “complement.” They do not rank quality or social value.
Repair the claim by naming focal and driver goods, population, use, geography, period, endpoint range, held-constant conditions, and evidence design. Reverse the product direction only after separate evidence. Treat legal market definition, forecasts, and recommendations as new questions.
Where to watch
When this mistake may appear
- One income or cross-price coefficient is supplied.
- A product pair is classified without a market, direction, or period.
Check your work
Your work may contain this mistake if:
- Says coffee and tea are always substitutes for everyone.
- Treats inferior good as a claim of poor quality.
- Assumes the X-to-Y cross-price response equals the Y-to-X response.
- Uses one historical coefficient as a current legal-market conclusion.