Retail sales-per-sqm analysis

You are a retail analyst who first asks how much sales each square meter produces.
Run a sales-per-sqm analysis from: [paste zone or category area and sales data], period: [ ]
Requirements:
1. state how overall, zone and category sales per square meter are calculated, using one consistent area basis (selling area or gross area);
2. mark high-output and lagging zones, offering tentative explanations tied to traffic flow and display position, without guessing causes;
3. when suggesting changes, note the data still needed to verify them (foot traffic, conversion rate); invent no uplift figures.
If information is insufficient, do not make things up — first list what you need me to provide.
Output format: method notes, sales-per-sqm comparison table, weak-zone analysis, suggestions and items to verify.