Probability/Impact Thresholds


Words on this page that have been underlined and italicized can be found in the glossary on the right-hand side of the page.

Overview

The probability/impact matrix is a grid for defining the probability and impact thresholds (e.g. L, M, H), which are used for ranking risks in the risk register. Two separate schemes can be saved: one for threats and one for opportunities.

Adjusting Thresholds

  1. Click the Risk  driver.

  2. Click the Rating button in the Risk Properties pane.

  3. Click the dropdown in the upper right-hand corner and choose between Threat and Opportunity.

  4. To change the number of probability thresholds, click the dropdown to the left of the Probability (%) column.

  5. Adjust the numerical probability value for each threshold as desired.

  6. To change the number of impact thresholds, click the dropdown below the Impact (Days) row.

  7. Enter an impact in days for each threshold.

  8. When finished, click the X icon to save and close the window.

When setting the qualitative probability for a risk in the risk register, the value from the Qualitative Thresholds window will be copied over to the quantitative probability, but only if the quantitative probability is empty. Subsequent changes to the qualitative probability or updating the value in the Qualitative Thresholds window will have no effect.

The thresholds are abbreviated as follows:

ThresholdAbbreviationDefault Value
Ultra HighUH100
Extremely HighEH95
Very HighVH90
HighH70
ModerateM50
LowL30
Very LowVL10
Extremely LowEL5
Ultra LowUL0

Thresholds may be thought of as a range of values or just a single value, whatever best serves the user. For example, "L" could be ≥30% but <50%; or it could be <30% but ≥10%; or it could be =30%; or it could be approximately 30%.

Risk Rating

The probability and impact thresholds are multiplied together and mapped from 0-100 to generate the risk ratings. NetRisk comes predefined with six different color schemes, as follows:

Color SchemeIdeal Use Case
FireFewer number of rating thresholds
ForestFewer number of rating thresholds
HorizonGreater number of rating thresholds
IceFewer number of rating thresholds
PondGreater number of rating thresholds
RainbowGreater number of rating thresholds

Tip

It is generally recommended to use a similar number of rating thresholds as probability and impact thresholds; however, there may be times when different levels of detail are desired.

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 Glossary

Impact (Qualitative): the degree to which the risk could affect activity durations. This is only used for qualitative purposes and has no role in the actual simulation.

Opportunity: a condition or situation that is favorable to the project, often having a positive impact or effect on duration.

Probability (Qualitative): the chance that a risk could occur. This is only used for qualitative purposes and has no role in the actual simulation.

Probability/Impact Matrix: a grid for defining the probability and impact thresholds (e.g. L, M, H) used for ranking risks in the risk register.

Risk Rating: the product of the probability with the impact, mapped from 0-100, to prioritize risks in the risk register.

Risk Register: an index of all possible threats and opportunities that may impact the schedule, along with their qualitative characteristics.

Simulation: a collection of one or more iterations taken together to represent or model a series of outcomes.

Threat: a condition or situation that is unfavorable to the project, often having a negative impact or effect on duration.