---
title: "Assess a risk"
url: "https://docs.4hse.com/risk-assessment/assess-a-risk"
description: "How to give a risk its initial value and measure the effect of the mitigation actions on it."
---

# Assess a risk

Assessing means giving the risk two values: what it is worth before the measures, and what it is worth after. The hazard must already be present in the phase and the risk must exist — see [Link sources, hazards and risks to a phase](/risk-assessment/hazards-and-risks).

## Give the initial value

[Section titled “Give the initial value”](#give-the-initial-value)

The work phase is in the **office** menu, under **Work phases**.

1.  Open the work phase and go to the **Risks** tab.
2.  Click the **Risk assessment** button inside the risk entry. The PxD matrix opens.
3.  Enter the **initial probability** and the **initial damage**. Their combination is the **initial risk**.

![The risk assessment matrix](/_astro/work-phases-5.DuIq5tWz_2dBow6.webp)

## Measure the effect of the measures

[Section titled “Measure the effect of the measures”](#measure-the-effect-of-the-measures)

Each mitigation action linked to the phase can be given an impact on probability and on damage. The combination of the initial values and those impacts produces the **residual risk**.

1.  Click the **Actions** tab at the bottom of the matrix.
2.  Click **New** and select the action.
3.  Set its **impact values** for probability and damage.
4.  Click **Save**.

![Setting the impact of an action on a risk](/_astro/risk-evaluation-matrix-5.B6Sf6REe_wegmQ.webp)

The **Risks** tab of the phase now shows three values for that risk: initial, variation and final.

![The final risk in the risks list](/_astro/risk-evaluation-matrix-7.DEVQMBi9_Z2itazQ.webp)

To change the values later, double-click the row or open it in a new window.

For the scales, the colours and the priorities, see [The PxD matrix](/risk-assessment/pxd-matrix).

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