Welcome to the third blog in our series exploring the key principle of schedule risk analysis. Last week we discussed the need for schedule integrity; this week we dive deeper into the topic of uncertainty and the value of three-point estimating.

Understanding Uncertainty in Schedule Risk Analysis

Uncertainty analysis allows you to better estimate how long things will take. When you create project schedules, generally you estimate with one figure how long an activity is going to take. With schedule risk analysis, however, we give each activity a three-point estimate. This is otherwise known as uncertainty.

Uncertainty works on the principle that whenever you estimate something there is always uncertainty on exactly how long it will take. This is still based on normal working conditions.  Risk on the other hand looks at things that could happen outside of normal working conditions.

Tools, such as Primavera Risk Analysis, allow you to model three-point estimates to give you percentage confidence levels of meeting targets, both for Finish Dates and Costs. From this you can then identify problem activities and in some cases come up with a plan to make them more certain.

Three-point estimates can be put in manually however there are several functions within PRA that can help you achieve this:

Quick Risk

The Quick Risk tool allows you to specify a percentage range for minimum duration, likely duration and maximum duration that it can then apply to all activities in your plan. It also allows you to specify the distribution type it uses, this includes Triangular, BetaPert and Uniform.

Templated Quick Risk

This can be used in three different ways:

  • Categories – allows you to set up a custom category field and create a series of different codes. You can then assign different percentage values to each code for min, most likely and max.  You then assign different categories to each activity and apply the percentages.
  • Summary Tasks – you can assign different percentage values for min, most likely and max to each different summary task in your schedule and this will be flowed down to the lower level tasks within each summary.
  • Advanced Filter – you can set up a series of different filters to apply to different activities. You can then assign different percentage values for min, most likely and max to each filter and apply these to your activities.

We hope you enjoyed this latest instalment of our Schedule Risk blog series.

If you missed the earlier blogs, here’s where you can find them:

Risk Register Set Up

Running Analysis

Schedule Integrity

To learn more about the tool and be fully confident to use it on your programmes, Underscore Training offer a comprehensive two-day Primavera Risk Analysis training programme. To find out more about our course please click the following link Primavera Risk Analysis. For a full list of public programme dates please see our website, Public Programme Dates.

Alternatively, if you have a group requiring training we can organise dates to suit you.

Please feel free to get in touch if you have any questions on 0203 9503730 or by email on training@underscore-group.com.

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