Start & End Dates
This article explains Start and End dates in the Timing modal.
You will learn:
How start and end dates bound accruals.
How they interact with frequency and schedules.
How changes to dates affect historical and forecast periods.
Start and end dates define the active window for a variable's accrual behaviour.
Where start and end dates are set
You set these dates in the Timing modal for each variable. For imported variables, they may be prefilled based on the imported series.
The fields usually include:
A start date calendar or picker.
An end date calendar or picker, which can be open ended in some configurations.
How start dates work
The start date is the first date on which the variable can accrue value.
Before the start date, accrual is zero.
On and after the start date, accrual follows the chosen frequency and schedule.
In models with historical data:
The start date may align with the first historical period.
Or it may be set to the first forecast period for new items.
Interaction with model start and end dates
The model itself has a start date and end date. Variable start and end dates are interpreted within that window:
If a variable's start date is before the model start date, accrued history before the model is usually represented only via opening balances.
If a variable's end date is after the model end date, only the portion within the model horizon is simulated.
Adjusting model dates may change which parts of a variable's life are visible.
Editing dates safely
When editing start and end dates:
Consider whether the change is a structural correction or a new business assumption.
For historical periods tied to imports, reducing the visible window will not modify the source data, only which part is used.
For future periods, extending or shortening the window alters the forecast horizon for that variable.
Use notes to document large date changes so reviewers understand the intent.
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