# Grouping Assumption Effects in Bridges
URL: https://docs.valsight.ai/grouping-assumption-effects-in-bridges/
Description: Combine the line-items of one assumption into a single bar in a bridge, or show each of them separately.
An assumption can be made up of several line-items. In a bridge, those line-items can either step through the chart one bar at a time or be combined into a single bar for the assumption as a whole.

## What it is

**Group Assumption Effects** is a toggle in a bridge's settings. It decides which of the two you get:

| Toggle  | What the bridge shows                                                    |
| ------- | ------------------------------------------------------------------------ |
| **Off** | One bar per line-item, so you can read the effect of each one separately |
| **On**  | One bar per assumption, combining its line-items into a single effect    |

With the toggle off, this assumption contributes two separate bars, both named **Volume**:

![A bridge with two separate bars, both labeled Volume](./images/5166563378.png)

With it on, those two bars become one:

![The same bridge with the two Volume bars combined into a single grouped bar](./images/5165907989.png)

## When to use it

* The bridge has become long and hard to read, and the individual line-items are more detail than the audience needs.
* You want the chart to speak in terms of assumptions rather than in terms of how those assumptions happen to be built.
* A line-item has several variants and you want the assumption's total effect rather than one bar per variant.

Leave it off when the point of the chart is which specific line-item moved the number.

## Configuration

1. Select the bridge. The chart editor opens on the right.
2. Go to **Bridge Settings**.
3. Switch **Group Assumption Effects** on or off.

## Good to know

* **It groups variants too.** When a bridge shows line-items with differing variants as deltas, rather than assumptions, the setting combines those variants into a single bar as well.
* **It is a display setting.** Grouping changes how the effects are drawn, never how they are calculated. See [Assumption Effects](/assumption-effects/).
* **It applies to both bridge types.** Scenario and time bridges both carry the toggle.

## Related

* [Assumption Effects](/assumption-effects/): how the effect of an individual assumption is derived.
* [Scenario Bridges](/scenario-bridges/): explain a difference between scenarios.
* [Time Bridges](/time-bridges/): explain a difference between periods.
* [Data Effects Display in Bridge](/data-effects-display-in-bridge/): the equivalent grouping for the model's own contribution.