# Data dictionary

**All records are fictional.** Keep the raw files unchanged and build your analysis separately. `rules.json` defines the population and assumptions. Blank, zero and unknown are not interchangeable.

## products.csv

One product, including one entrant and one exit.

| Field | Meaning |
|---|---|
| `product` | Stable product identity across both periods. |
| `old_units` | Prior units sold. Zero identifies the entrant’s absence in the prior period. |
| `old_price` | Prior price in USD per unit; blank when old_units is zero. |
| `old_unit_cost` | Included prior variable cost per unit; blank when no prior units. |
| `new_units` | Current units; zero identifies an exited product. |
| `new_price` | Current USD price per unit; blank for an exit. |
| `new_unit_cost` | Current included variable cost; fixed costs, taxes and capacity changes are outside the model. |