Every model computes one grid: each driver, at each slice, at each step.
A model produces one grid, and the grid has three dimensions: driver, slice, and step. A driver is a quantity the model computes, such as MRR, and it is one row. A step is one position along the dimension the model walks, such as a month. A slice is one combination of the model's other dimensions: the pro plan, in the US, at high growth.
A cell is one driver at one slice at one step. It holds exactly one value.
Calcbird computes every driver at every slice at every step, together. There is no choosing one combination and running it. A model with four drivers, twelve slices, and five steps is a grid of 240 cells, and one run produces all of them.
plan = pro, scenario = steady
2024-01 2024-02 2024-03 2024-04 2024-05
Invoices 1 2 1 1 1
Revenue 1000 2000 1500 1650 1815
ARPU 1000 1000 1500 1650 1815
NetRevenue 800 1600 1200 1320 1452The example above is one slice of that grid. The other eleven slices have the same drivers and the same steps, with the numbers for their own plan and scenario.
A model that walks one dimension and has no others has exactly one slice. Its grid has drivers down the side and steps across the top, which is the shape most spreadsheets start as.