Step 5.1: Carry out bottom-up estimates
Some top-down estimates of effort, cost and duration will already have been done (see Step 3.6).
Chapter 5 on Software At this point, estimates of the staff effort and other resources required, and the
Estimation deals with this probable elapsed time needed for each activity will need to be produced. The topic in more detail. method of arriving at each of these estimates will vary depending on the type of activity.
The individual activity estimates of effort should be summed to get an overall bottom-up estimate, which can be reconciled with the previous top-down estimate.
The activities on the activity network can be annotated with their elapsed times so that the overall duration of the project can be calculated.
Step 5.2: Revise plan to create controllable activities
The estimates for individual activities might reveal that some are going to take quite a long time. Long activities often make a project difficult to control. If an activity involving system testing is to take 12 weeks, it might be difficult after six weeks to judge accurately whether 50% of the work is completed. It would be better to break this down into a series of smaller sub-tasks.
Case Study Example: IOE Maintenance Group Accounts - breaking activities down into manageable tasks
At IOE, Amanda has to estimate the lines of code for each of the software modules. She looks at programs that have been coded for similar types of application at IOE in the past to get some idea of the size of the new modules. She then refers to some conversion tables that the information systems development department at IOE have produced; these tables convert the lines of code into estimates of effort. Other tables allow her to allocate the estimated effort to the various stages of the project.
Although Brigette is aware that some additional programs might have to be written to deal with local requirements, the main software is to be obtained 'off-the-shelf' and so estimating based on lines of code would clearly be inappropriate. Instead, she looks at each individual task and allocates a time. She realizes that in many cases these represent 'targets' as she is uncertain at the moment how long these tasks will really take (see Step 6 below).
Was this article helpful?
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.