Step Nine: Document Estimate and Lessons Learned
Each time you complete an estimate and again at the end of the software development, you should document the pertinent information that constitutes the estimate and record the lessons you learned. By doing so, you will have evidence that your process was valid and that you generated the estimate in good faith, and you will have actual results with which to calibrate your estimation models. Be sure to document any missing or incomplete information and the risks, issues, and problems that the process addressed and any complications that arose. Also document all the key decisions made during the conduct of the estimate and their results and the effects of the actions you took. Finally, describe and document the dynamics that occurred during the process, such as the interactions of your estimation team, the interfaces with your clients, and trade-offs you had to make to address issues identified during the process. Cost models, which are based on the actual costs of past projects, can be calibrated and their accuracy can be demonstrated by comparing the costs of your current estimates with both past project data and the actual costs of your completed project, thereby adjusting the model input parameters to improve future accuracy.
Step Eight: Generate A Project Plan
The process of generating a project plan includes taking the estimate and allocating the cost and schedule to a function and task-oriented work breakdown structure. Models such as SEER Client for Microsoft perform this function automatically. The eight major software development phases
are: (1) concept, (2) acquisition, (3) requirements, (4) design, (5) code and unit test, (6) integration, (7) acceptance, and (8) post deployment.
Determining Costs from Effort Estimates
At this point in the estimation process, you should have a reasonably accurate projection of your project’s size and required effort, that is, an estimate of the number of person-hours by component and a sum of these projections, and you can now begin to price the estimate. As software estimation models generally account only for costs related directly to development, you may need to translate the required effort to a cost and finalize the estimate by adding in essential nonlabor costs. You can do so by answering the following questions:
What types of individuals do I need and when do I need them?
Identify the specific personnel requirements by task area (direct software management, software systems engineering, design, programming, configuration management, quality assurance, etc.). Develop a strawman schedule from the work breakdown structure or a staffing plan such as the one produced by SEER-SEM.
How experienced do they have to be? Assign specific staff levels to the task requirements and identify the level of experience required to satisfy the task. Some of the automated cost models will identify the tasks and develop a task-based schedule, which will minimize but not eliminate all of the work required to produce the software development plan.
Step Five: Prepare Baseline Estimate
Budget and schedule are derived from estimates, so if an estimate is not accurate, the resulting schedules and budgets are likely to be inaccurate also. Given the importance of the estimation task, developers who want to improve their software estimation skills should understand and embrace some basic practices. First, trained, experienced, and skilled people should be assigned to size the software and prepare the estimates. Second, it is critically important that they be given the proper technology and tools. And third, the project manager must define and implement a mature, documented, and repeatable estimation process.
To prepare the baseline estimate there are various approaches that can be used, including guessing (which is not recommended), using existing productivity data exclusively, the bottom-up approach, expert judgment, and cost models.
Software Productivity Laws
These laws of software productivity help explain the dynamics of an engineering development project, and they illustrate some of the reasons that just using productivity to estimate is inadequate.
Law 1 - Smaller teams are more efficient. The smaller the team, the higher the productivity of each individual person.
Law 2 - Some schedule compression can be bought. Adding people to a project, to a point, decreases the time and increases the cost as larger teams work together.
Law 3 - Every project has a minimum time. There is an incremental person who consumes more energy than he or she produces. Team size beyond this point decreases productivity and increases time. (Law 3 is also known as Brooks’ law.)
Ten-step Project Estimation Process
Software Estimation Concepts
Many project managers and project management offices have unrealistic expectations about estimates. The definition of the verb estimate is to produce a statement of the approximate value of some quantity. Estimates are based upon incomplete, imperfect knowledge and assumptions about the future. For these reasons, many estimates of software costs tend to be too low due to omissions of important product functions and project activities. Most importantly, however, all estimates have uncertainty. There is no such thing as a precise, single-value estimate. Managers should always ask how large the uncertainty of an estimate is! A manager can use the size of this uncertainty in conjunction with other factors such as perceived risks, funding constraints, and business objectives to make decisions about a project.
How can projects address the uncertainty of poor estimates? How can the risks associated with initial estimates be identified, managed, and controlled? The answer is straightforward: by defining, establishing, planning, and applying a consistent, repeatable, and effective estimation process.
A software estimation process that is integrated with the software development process can help projects establish realistic and credible plans to implement the project requirements and satisfy commitments. It also can support other management activities by providing accurate and timely planning information. Realistic plans will also describe how the resources that are required to undertake the initiative in accordance with the schedule will be secured. The planning process, as critical as it is, is difficult and takes time to perform correctly. Managers often truncate the planning process by using “easily available” information that is often inadequate; by employing whoever has the time, even if those individuals are not qualified to perform the estimate; and by using only one estimation method to save time.
Successful software engineering requires the application of engineering principles guided by informed management. The principles must them-selves be rooted in sound theory. While it is tempting to search for miracles and panaceas, it is unlikely that they will appear. The best course of action is to stick to age-old engineering principles. There simply are no silver bullets.
Cost estimates are projections of required effort, time, and staffing levels. Because all estimates, particularly those made at the beginning of a project, are based on assumptions, they should be considered probabilistic. Cost estimates in particular should provide a range with an indication of accuracy, i.e., least, probable, and most, with the least and most values representing the upper and lower bounds of the projected cost.
Project Estimation Process
Ideally an estimate should be produced using the ten-step process.
During October we will cover each step on this blog.
Figure 1 Ten-step project estimation process
- Establish estimate scope
- Establish technical baseline, ground rules & assumptions
- Collect data
- Size software
- Prepare baseline estimates
- Quantify risks & risk analysis
- Review, verify, validate estimate
- Generate a project plan
- Document estimate & lessons learned
- Track project throughout development
Performance Based Earned Value
It has been very interesting reviewing Paul Solomon’s Performance Based Earned Value. It is in many ways consistent with SEER’s monitoring and control. It preaches looking at quality in addition to quantity of work performed as well as capturing the issues of deferred functionality. I should point out that we sometimes called SEER’s Monitoring & Control Performance Based Earned Value before we realized it was trademaked. Since we have stuck with 4 dimensional earned value for SEER.
PBEV has 16 guidelines in addition to the 32 included in the EIA 748 earned value standard. Read more
Software Development Metrics At Galorath: Co-located Teams Are Still Most Efficient
Our Development Vice President, Karen McRitchie and myself had an interesting review of development productivity in our own organization. Very interesting, but no surprises.
She found that the most productive projects are those where the team is co-located. There is a productivity hit when the team is geographically disbursed. Of course SEER for Software estimates reflect this with their multiple site parameter. But some people, even within Galorath, attempt to deny this phenomenon. Read more
SEER Helps Avoid “Fact Free Planning”
While at a conference last week someone discussed “fact free planning” I had not heard the term before but was intrigued. Fact free planning goes back to an article by MIT’s Sloane School, “How Project Leaders Can Overcome the Crisis of Silence”.
Fact free planning happens, in part when someone (business development, executive, etc… not one with project team responsibility) makes commitments to stakeholders. The article discusses how such behavior in part spawns padded estimates.
Many times project scheules and budgets come down from above without regard to project realities.
Project people pad schedule and cost estimates expecting them to be ignored or changed anyhow. Then when several levels of managers pad or cut feeling that the estimates have been padded any semblance of reality becomes lost.
The authors go on to discuss how unhealthy organizations attempt to avoid conflict and how that conflict avoidance hides problems.
One fix for fact free planning is an environment where participants are safe in communicating truth. SEER attempts to eliminate fact free planning by providing estimates: simulations of project realities based on ranges of probable outcomes.
