Estimating Guidelines act 1 of 2

When to estimate, and who estimates

Estimates are essential both to ensure that finance can be reserved for the project, but also so that the project manager has a baseline to control the project against.

Estimates will be revised throughout the duration of a project, but there are two main points where estimates are developed.

1. During the drafting of the Project Brief an initial rough estimate of the effort required to complete the project should be produced. This will help to assess whether the project is viable.
2. After the project brief has been signed off, more detailed estimates for the Project Plan.

Before the start of each major piece of work, review the estimates in the light of experience and to reflect changes in what is to be delivered. 

The following general principles may help:

1. Wherever possible, get more than one person to do the estimating, and include the people who will be doing the work.
2. Do not rely on just one estimating technique.
3. Capture actual data, compare the data with original estimates, and feed this into the estimating process.
4. Document all assumptions that have been made in support of the estimating process.
5. Describe estimates with a tolerance to indicate the level of confidence (e.g. or - 20%).
6. Estimates should cover all requirements.

Developing Estimates

First, ensure you know what is involved in the project - in particular what work will be involved. This information can be found in the project brief and project plan.

Next, consider what resources you will need. Take into account the scope and complexity of the project and the range of skills that will be needed. If it helps, break the tasks down into smaller tasks.

Then, establish what can be resourced internally, and what will need to be resourced by people with specialist skills, possibly including bought-in resource.

The final step involves estimating how much effort (i.e. the number of person-days of work) will be involved to complete specific project tasks and activities.

( to be continued )

Additional resources:

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Massimo Antoniello is a business and solutions architect with more than 20 years of experience supporting business growth and development, in various industries