Impact analysis is done, the application scope is determined to understand what all applications are within and out of scope depending on which upstream and downstream applications are identified. These have significant bearing on integration and end to end testing.
1. Correct estimations are pre requisite to successful project management
2. Accurate project estimates for a proposal ensure that -
- Project estimates are not too high, a proposal is not rejected.
- Effort and schedule estimates are not too low, thereby avoiding cost overruns and schedule delays in the proejct
- On receipt of a RFP from client
- Immediately on project initiation
- Beginning of each phase of the project (this varies for the type of project - Development, Maintenance, Conversion)
- Upon receiving CRs or Requests for Enhancements
Estimation @ RFP stage:
- Based on data given in the RFP
- Less data / knowledge available
- Low level details are not available
- May cover the following:-Estimate for each business function of the total requirements-Add overheads for quality assurance, project management-Estimate efforts for new technology, new tools, etc-Contingency
What to Estimate?
Estimate the Size, which then leads to estimation of schedule and effort.
In what units is Size estimated?
Size of work product is estimated in:
- Feature Points
- Number of Requirements
- Number of Components
- Estimation based on Use Cases for Object Oriented Projects
How is Effort derived from Size?
Productivity figures are taken into consideration. Also, COCOMO is used. Overheads for other activities are added (for example, User documentation, project management, quality assurance, user training, etc.). Note that in all these cases, complexity of the system to be designed and technology used must also be taken into account.
How is Schedule derived from Size?
T(in months) = y * 2 sqrt Effort in Person Years
- y is typically 2.5 to 3.0 for projects of effort <=180 person months
- y is typically 2. to 2.5 for projects of effort > 180 person months
While deriving Schedule take into account the leaves, trainings, and contingency.
What other things have to be estimated for?
- Team Size, Critical Computer Resources, Quality Assurance
- What factors affect estimations?
- Programmer experience
- Project documentation
- Training Effort
- Assumptions and Dependencies
- Management time
- Attrition, etc.
Other things to be factored in
- Knowledge and experience of the estimator (skill level of the estimator)
- Level of details available for estimates
- Time spent on understanding requirements and estimating
- Method used for estimation
Finally, what steps are involved in Estimation?
- Identify the complexity level of each work item, obtain the figures for effort ratio for various phases and get the productivity figures for various phases
- Use an appropriate estimation model, finalize the estimate for each phase of the project.
- Document methods and calculations used for estimation, assumptions made, constraints taken into account, and loading plan
- Consider experience of the team in the application area, exp of the team with the programming language, use of tools and s/w engg practices, and required schedule
- Monitor these estimates continuously to track any change in the assumptions, constraints and loading plan