Estimates

1. Estimates • Estimates • Uncertainties • Unknown • Project development costs • Project development schedules • Team size • Amount of software to be developed • Hardware resources

2. Estimates • Stepwise Estimation • Divides a large problem into numerous smaller problems. • The basic approach decomposes the project into well-defined components, then to iterate step-by-step until only small units remain, which can be easily estimated.

3. Estimates • Stepwise Estimation • Project Decomposition by level of risk • Off-the-shelf components • Full-experience components • Partial-experience components • New development Software Development Project New development Partial experience Full experience Off-the-shelf Minimal Risk High risk Reasonable risk Some risk involved

4. Estimates Charter Approval Plan Approval Pre-Launch Launch Execute Size Estimates (Macro) Task-based Estimates Project Schedule +/- 35% range +/- 15% range +/- 10% range • During the Pre-Lunch stage, the overall project strategy is developed. From the strategy, size (macro) estimates are developed. Size estimates should not be converted to schedules • During the Launch stage, comprehensive plans and detailed (micro) estimates are developed • During the Execution stage, task-based estimates are converted into resources and calendar specific schedules Note: At all stages, both management and the project team must be willing to acknowledge the need to modify estimates whenever events so dictate.

5. Estimates • Size (macro) Estimates • Used to serve two key purposes • Used by management to decide if the project is feasible • Assess the effects of the proposed project on the portfolio of current and proposed projects • Not suitable for developing project schedules because can have +/- 35% differences from actual.

6. Estimates • Size (micro) Estimates • The objective is to develop effort, cost, resources and duration values. • It is suitable for creating a resource-specific project schedule. • Efforts – the work hours it takes to complete a given amount of work. Effort is greatly affected by the knowledge, experience, and the work environment of the person performing the task. • Duration – the number of work days needed to completed the task. Duration estimations are affected by the percent assignment and resources available • Resources – the number of (core) team members and their skill levels • Cost – obtained by multiplying the estimated effort by appropriate billing rates. Additionally, any overhead and cost of non-human resources must be added: hardware, facilities, and so on. • Detailed estimates can have +/- 15% difference from actual, hence range should be acceptable.

7. Estimates • Sizing techniques /models • Project size (macro) estimates are developed using the sizing models • These models statistical paradigms used to generate high-level effort, duration, and cost projections at a point when little is known about the project • Effort Distribution Models (EDM) • Deliverables-Based Estimates • Functional Point Estimating Models • Sizing techniques are most applicable to new development and major enhancements.

8. Effort Distribution Models Estimates (EDS) • EDS • In this method, an effort distribution model is expressed as a percentage of total effort, is created for each phase of the project lifecycle. • Efforts – the work hours it takes to complete a given amount of work. Effort is greatly affected by the knowledge, experience, and the work environment of the person performing the task. • This data can be collected from in-house projects, if comprehensive and accurate time reporting systems exists, or published industry data.

9. Estimates • EDM This figures are from an actual project

11. EDM • Steps • Develop detailed task based effort estimate for the first 15-20% of the project. Document resources (skill) assumptions. • Using the estimates effort as a base, extrapolate the effort for each of the remaining project phases • Convert the extrapolated phase effort into phase duration and estimate the number of resources needed for each phase • Plot a phase-based Gantt to depict phase execution order and overlaps, if any. This will result in the estimated duration for the project • Estimate the amount of project management effort for the project

12. Estimation (EDM) Remember that model base provides a base reference and actuals may differ due to project specific variances. Of course, if the actuals continue to differ considerably from the model, the model should be recalibrated and effort distribution recomputed.

13. Estimation (EDM) • Converting effort hours into estimate durations. • Convert the estimated phase effort hours to work months by dividing the total hours by the average production hours per month per person. • 6.5 work-hours per day and 17.5 work-days per month = 114 • Determine the Optimal Full-time Equivalent (OFTE) team members for each phase by taking the square root of the work months computed above • Compute the estimated phase duration as • Phase duration = work months / OFTE • Develop a phase-base Gantt – depict the order of phase execution and appropriate phase overlaps and determine the duration estimate in terms of work-days, works weeks, or work-months. • Problems • Effort for user participation are usually not included • A full-time PM for a 7 FTE team member. That is one FTE will consume 15% of PM’s time.

14. Estimation (EDM)

15. Estimation (EDM) 0 month 10 months 20 months 30 months ED ID CUT SAT IN PI PM Effort 0 month 10 months 20 months 30 months ED ID CUT SAT IN PI