Sales Forecasting with Scenarios and Weekly Refresh

![Sales forecast demonstration: scenarios, validation and refresh](https://www.twine.net/signin

Synthetic demonstration.

Sales planning needs a forecast that managers can inspect, update and compare with their targets. I created a working model that keeps sales volume, sales value and business assumptions connected.

Using 156 weeks of generated history across four product-and-segment series, I compared two seasonal methods on earlier validation windows, then froze the selected method before a separate 26-week holdout. This makes the method-selection process and its timing visible to the reader.

The deliverables are a six-sheet Excel workbook, a two-page case study and a command-driven weekly refresh tool with sample input and instructions. One scenario selector updates the same forecast model across pessimistic, realistic, stretch and optimistic cases. Product and segment totals reconcile to the business total, while actual weeks remain unchanged.

The recorded holdout unit WAPE was 5.34%, compared with 10.20% for the seasonal-naive benchmark. All four workbook scenarios reconciled to independent calculations. An added-week refresh preserved user assumptions, formulas and charts, and the refreshed file recalculated with zero formula errors in the tested spreadsheet engine.

These are demonstration results. Scenarios describe assumptions, not calibrated probabilities. The current model uses four fixed series and complete positive weekly data; desktop Excel and client-specific calendars still require acceptance testing.

The working workbook, refresh tool and illustrated PDF are prepared and available for review.

[Open the illustrated model walkthrough](https://www.twine.net/signin