Time Segment Setup

How to create and edit Time Segments

Creating/Editing Time Segments

Time Segments are managed in the Time Segments step of the Variable dialog.

Time Segment step of the Variable dialog

You can add, edit and duplicate Time Segments just like any other item in a list view.

The Time Segment Wizard

Timings

You must define the time period over which each Time Segment applies. This time period is defined in terms of three settings:

1. From: The period at which the segment starts

2. Duration: The length of the segment

3. To: The period at which the segment ends

As shown in the screenshot below, these settings can be quickly edited by clicking on the relevant editing shortcut button .

Timings editing shortcuts

From and To settings can be set to one of the following:

From/To setting	Details
Auto	Period dependent on context: If first segment, From will be set to the start of the model If last segment, To will be set to the end of the model If other, From/To will be based on end or beginning of adjacent segments).
Fixed Period	Choice of specific periods from the Model timings (e.g. Q2 2030)
Periods from Start	Number of periods from start (first period = 1 )
Periods from End	Number of periods from end (last period = 1)

Duration can be set to one of the following:

Duration setting	Details
Fill	Segment will stretch to end of previous period and beginning of next (or to start/end of the model if first/last segment)
Number of periods	Segment will occupy the specified number of periods

You should apply a maximum of 2 of the three settings. Which settings are applied depends on the Time Segment.

For instance, the first Time Segment never needs to have the From setting applied, as it always starts at the first period. If you set From to a period that is not the first period, a warning will be shown.

Likewise, if you set both the Duration and the To settings of the first Time Segment, one of these will be redundant, and they may clash.

Formula

The Formula of a Time Segment determines how that Time Segment calculates its values.

There are five possible formula types for each Time Segment:

Formula Type	Details
Auto	Applies the default Calculation of the Variable. (This option is not available for an Assumptions Type Variable).
Assumptions	Links to specific Assumptions. See Creating/Referencing Assumptions for more details.
Calculation	Applies a custom Calculation that cannot refer to other Variables. (See more details below).
Aggregation	Used for an Aggregation Variable. Cannot be manually selected - applied automatically when using Aggregation.
Rearranged	Used when Rearranging. Cannot be manually selected - applied automatically when Rearranging

Calculation Formula

Example of Calculation Formula

As shown in the above example, a Time Segment with a Calculation formula acts similarly to an Assumptions Time Segment.

In this example, Price inflation is a Variable of type Assumptions. In the first period, an Assumptions Time Segment links to an input. We then use a Calculation Time Segment for the remaining periods to reference the previous period, rather than linking to specific Assumptions for each period of the Model.

Calculation Time Segments act similarly to Assumptions, in that they specify an input to the Model. For this reason, calculations in Time Segments cannot reference other Variables.

If you want to perform a calculation referencing other Variables, the Variable itself must be of type Calculation.

If you are not sure when to use Assumption/Calculation Variables and Assumption/Calculation Time Segments, you may want to read about the Rearranging feature, which helps deal with complex scenarios.

Time Segment shortcuts

Time Segment shortcuts

Several shortcuts are provided in the Time Segment interface to speed up some common operations, as shown in the image above.

Shortcut	Details
1) Insert period	Inserts a period of duration 1 period at the start of the Model
2) Make all equal to first period	Inserts a single period segment of type Assumptions at the start of the Model, and a second segment with a Calculation of Variable [-1] for the rest of the Model timings (as per the example shown in the image above).
3) Change formula type	Opens a dropdown to quickly switch between formula types.
4) Reset to default segment type	For a Calculation Variable, resets Time Segment to Auto. For an Assumptions Variable, resets Time Segment to Assumptions.