Product 4 |
123456789 10 Timescale (days)
Figure 7.11 describes some of the time-related characteristics of each product, with an example box identifying what is meant by the numbers:
e est - earliest start time. The earliest point at which the task or product may commence. e eft - earliest finish time. The earliest point at which the task or product may be completed. e lst - latest start time. The latest point at which the task or product may commence before it affects others. e lft - latest finish time. The latest point at which the task or product may be completed before it affects others. e dur - duration. The number of working days between the est and the eft, or the lst and lft. e fl - float. The difference between the est and the lst or the eft and the lft. This is the amount by which the task or product may slip before it affects others.
In the example, product 1's capacity to slip is shown because it has a float of 4, but all the others have none. Because of their zero float, products 2, 3 and 4 are on the critical path; any slippage by any task or product on this path will result in an identical slippage in the project's end date.
A project may have more than one critical path and any of them might change during the course of the project as the float capacity is consumed by slipping tasks. Therefore, the critical path(s) is an area of risk in the project.
The fact that product 1 has some float may be helpful to the project manager. What would the effect be if product 1 were started later?
In Figure 7.12, product 1 has been allowed to start later with no effect on the project's end date. If managing the timescale and quality were the only things that mattered, this might be an acceptable change. However, since the project manager must also manage the budget, the effect of this change on the resource plan also needs to be determined. It may have been impaired already because pr is scheduled to develop both product 1 and product 3 at the same time.
As suspected, the effort planned for days 1 and 2 has shuffled across to days 4 and 5, and pr has become overcommitted on day 4. The likely consequence is that the project will slip, or the quality of product 1 will suffer as pr tries to keep within the deadline.
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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.