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The secret of good estimation

At this time of year, the various departments of the university are planning their activities and budgets for next year.  Applications Division provide the IT component of many new projects, so we are asked to estimate how much time and money will be required or a wide range of proposals.  Most of these proposals are at preliminary stages, with only outline ideas of what will be required.  Given this uncertainty, You might ask what is the secret that lets us produce accurate estimates for all these proposals?

The truth is: we don't.  Of course, we look at our project record to see how much effort was required for similar projects in the past.  This data gives us a guide to the costs of different types of project, such as software procurements, infrastructure upgrades, and software development.  The data also helps us allocate the expected effort across the different teams that will be involved.  But we often don't know exactly what a project will entail and there is usually a large element of uncertainty.

The key is that these estimates should be the start of a conversation, rather than the end of a process.  Although they give people a sense of the likely scale of a project and help us plan our future work, they cannot be set in stone.

For most projects, the work of the project is an ongoing process of knowledge elicitation.  Everyone involved will be aiming to improve their understanding of what the IT system needs to achieve and how it will help people achieve their actual goals.  New features may be proposed, previous assumptions may be overturned, and technical problems may occur.  Often the project team will face a choice: either increase the budget to achieve more features, or reduce the project scope to fit the budget. 

So the budget that accompanies an initial proposal is always provisional, always contingent.  When the project starts, so does the process of refining the estimate as we learn more about the special attributes of that particular project.

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