Exercise 10: Scenario-based management analysis

Use data/stagnant_retail.csv.

1. Plot monthly average sales.
2. Plot monthly average marketing spend.
3. Plot monthly average competitor pressure or footfall.
4. Fit the working sales regression used in the lesson.
5. Create a baseline using medians.
6. Add a new scenario: discount_pct + 3.
7. Add a stress scenario: footfall_k - 5%.
8. Use predict(..., interval = "confidence").
9. Rank the scenarios by predicted mean sales.
10. Write a 100-word management memo distinguishing:

• descriptive diagnosis;
• model-based scenario prediction;
• causal evidence.

11. Explain why repeated monthly observations within branches connect this case to multilevel analysis.