Where are estimates done

Estimates are carried out at various stages of a software project. At each stage, the reasons for the estimate and the methods used will vary.

Strategic planning The costs of computerizing potential applications as well as Chapter 3 discusses the benefits of doing so might need to be estimated to help decide what priority to strategic planning in some give to each project. Such estimates might also influence the numbers of various detail, types of development staff to be recruited by the organization.

Feasibility study This ascertains that the benefits of the potential system will justify the costs.

System specification Most system development methodologies usefully distinguish between the definition of the users' requirements and the design that documents how those requirements are to be fulfilled. The effort needed to implement different design proposals will need to be estimated. Estimates at the design stage will also confirm that the feasibility study is still valid, taking into account all that has been learnt during detailed requirements analysis.

The estimate at this stage cannot be based only on the user requirement: some kind of technical plan is also needed - see Chapter 4.

Evaluation of suppliers' proposals In the case of the IOE maintenance group accounts subsystem, for example, IOE might consider putting the actual system-building out to tender. Staff in the software houses that are considering a bid would need to scrutinize the system specification and produce estimates on which to base proposals. Amanda might still be required to carry out her own estimate to help judge the bids received. IOE might wish to question a proposal that seems too low: they might wonder, for example, whether the proposer had properly understood the requirements. If, on the other hand, the bids seem too high, they might reconsider in-house development.

Project planning As the planning and implementation of the project progresses to greater levels of detail, more detailed estimates of smaller work components will be made. As well as confirming the earlier and more broad-brush estimates, these will help answer questions about, for example, when staff will have completed particular tasks and be available for new activities. Two general points can be made here:

• as the project proceeds, so the accuracy of the estimates should improve as knowledge about the nature of the project increases;

• conventional wisdom is that at the beginning of the project the user requirement (that is, a logical model of the required system) is of paramount importance and that premature consideration of the physical implementation is to be avoided. In order to do an estimate, however, the estimator will have to speculate about this physical implementation, for instance about the number of software modules to be written.

To set estimating into the context of the Step Wise framework (Figure 5.1) presented in Chapter 1, re-estimating might take place at almost any step, but specific provision is made for it at Step 3, 'Analyse project characteristics', where a relatively high-level estimate w ill be produced, and in Step 5 for each individual activity. As Steps 5-8 are repeated at progressively lower levels, so estimates will be done at a finer degree of detail. As we w ill see later in this chapter, different methods of estimating are needed at these different planning steps.

Parkinson s law was originally expounded in C. Northcote Parkinson's tongue-in-cheek book Parkinson's Law, John Murray. 1957.

Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

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