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Software Engineering II. Feasibility Studies. Feasibility Study. A feasibility study is a study made before committing to a project. A feasibility study leads to a decision: go ahead do not go ahead think again
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Software Engineering II Feasibility Studies
Feasibility Study A feasibility study is a study made before committing to a project. A feasibility study leads to a decision: go ahead do not go ahead think again In production projects, the feasibility study often leads to a budget request. In research, a feasibility study is often in the form of a proposal.
Why are Feasibility Studies Difficult? Benefits are usually very hard to quantify. Approach is usually ill-defined. Estimates of resources needed and timetable are very rough. Organizational changes may be needed. Therefore, feasibility studies rely heavily on the judgment of experienced people. Who are often over-enthusiastic. Mistakes made at the beginning are the most difficult to correct.
The Decision Maker's Viewpoint A senior member of an organization must decide whether to begin a major software project. What information is needed? Client: Who is this project for? Scope: What are the boundaries of the project? Benefits: What are the benefits? Can they be quantified? Technical: Is there at least one technical way to carry out the project? Resources: What are the estimates of staff, time, equipment, etc? Alternatives: What are the options if the project is not begun?
The Decision Maker's ViewpointWhere are risks? Can they be minimized? Technical • There must be an outline plan with a rough timetable and staff allocation. • The plan must have a very large margin for contingencies. (Projects typically require twice the staff and/or time envisaged in the feasibility plan.) External • Every system interacts with others. Are the others committed to the necessary efforts? • Where are the external pressures and obstacles?
Example 1: U.S. Government Agency(Decision before Feasibility Study) Outline Description A U.S. government agency, which manages huge numbers of documents and other records, has been very slow in moving from a paper based approach to managing digital documents.
Example 1: Chronology • A scientific computing center at University of California was commissioned to develop a prototype system to demonstrate technology. • Funds were approved by Congress to "procure" a major computer system. • The National Academy of Sciences was commissioned to report on the technical approach to be followed and the results of the University of California prototype (feasibility study). Note: The decision to go ahead was made and the budget approved before the feasibility study was begun.
Example 1: National Academy Report • The National Academy study finds: • The computer system is technically feasible. • The University of California prototype is promising but incomplete. • Agency needs stronger technical staff. • The study was not asked to comment on external factors, • but discovered major weaknesses in the agency's • management structure and organizational skills.
National Academy Report:Technical Recommendations The study recommends a phased approach: 1. System architecture created by iterative refinement to create a Phase 1 design. Followed by sequential implementation using the Phase 1 design
Example 1: Prototype and Phased Development • A prototype is not released to users, except experimentally • In phased development, each phase is released into full production UC prototype Build phase 1 Build phase 2 Developers Demonst-ration only Phase 1 production Phase 2 production Users Sequential process Iterative process
Example 1: Obvious Problems • Organizational: • Agency senior management clearly not ready to lead a very large project that will completely change the agency • No thought given to the workflow and job changes that will affect almost every member of staff • Preparation: • No preliminary study made of volumes or kinds of data; nor of the very complex access policies • Complexity • Major changes in the requirements and design are inevitable once the system goes into production and has real users
Example 1: Dilemma • Agency does not want to return money to Congress • National Academy study was paid for by agency and restricted to technical considerations • The fundamental problem lies at the senior management level • [A phased approach over many years might possibly work, but • only after the organizational problems are addressed.] • The agency has adopted a pure waterfall model and put out a Request for Proposal for the Requirements • This is a disaster in the making.
Feasibility Study: Scope • Scope expresses the boundaries of the system: • It will include <list of included functions> • It will exclude <list of excluded functions> • It depends on <list of dependencies> • It replaces <list of functions to be replaced> • Confusion over scope is a common reason for clients to be • dissatisfied with a system. • "Is that all you planned to do?" "But I assumed that you were going • to do xyz." "I can't use the system without abc."
Example 2: Library of CongressConfusion over Scope • The Library of Congress required a repository system to store and make accessible very large amounts of highly varied material over long periods of time. • An outside organization (CNRI) built a repository system to store and manipulate complex digital objects • Nobody built the sub-systems needed to organize, validate, and to load material into the repository. • The Library of Congress expected the repository system to include this sub-system. CNRI considered it external to the repository system • A good feasibility study would have seen this confusion.
Feasibility Study: Benefits Why is this project proposed? Can you quantify the benefits? Examples • Create a marketable product • Improve the efficiency of an organization (e.g., save staff) • Control a system that is too complex to control manually • New or improved service (e.g., faster response to customers) • Safety or security
Example 3: Benefits of the National Science Digital Library (NSDL) Concept Create a comprehensive digital library for all aspects of science education, where science and education are both defined very broadly. The National Science Foundation studied potential benefits for five years before going ahead. It came to the conclusion that, even though the benefits could not be quantified, the potential was sufficient to justify a major program.
Example 3: NSDL Timetable 1996Vision articulated by NSF's Division of Undergraduate Education 1997National Research Council workshop 1998SMETE-Lib workshop 1999NSDL solicitation 20006 demonstration projects of the core system 2001 Core integration system funded Note: 5 years from concept to decision to definitely go ahead.
Feasibility Study: Technical • A feasibility study needs to demonstrate that the proposed system is technically feasible. This requires: • a rough outline of the requirements • a possible system design (e.g., database, distributed, etc.) • estimates of numbers of users, data, transactions, etc. • possible choices of software to be acquired or developed • These very rough numbers are fed into the provisional plan that is used to estimate the staffing, timetable, equipment needs, etc. • The technical approach actually followed may be very different.
Feasibility Study: Planning and Resources • The feasibility study should include an outline plan: • Estimate the staffing and equipment needs, and the preliminary timetable • Identify major decision points • Identify interactions with and dependences on external systems • Provide a preliminary list of deliverables and delivery dates
Feasibility Study: Alternatives and Risks • A feasibility study should identify alternatives and risks. • Alternatives • Continue with current system, enhance it, or create new one? • Develop in-house, or contract out? (How will a contract be managed?) • Risks • What can go wrong? • How will problems be identified (visibility)? • Are there fall-back options?
Techniques for Feasibility Studies Give client appreciation of system: demonstration mock-up walk through Outline budget: n people for m months at $x per month equipment, buildings, etc. Phases/milestones: deliverables at approximate date
Feasibility Report A written document • For a general audience: client, financial management, technical management, etc. • Short enough that everybody reads it. • Long enough that no important topics are skipped. • Details are often included in supporting documents. It should be a well written, well presented document.
How to Minimize Risk? • Several target levels of functionality: required, desirable, optional phases • Visible software process: intermediate deliverables • Good communication within team and with Teaching Assistant Good processes lead to good software Good processes reduce risk
Feasibility Report • Specific Requirements for the Feasibility Report • Outline plan, showing principal activities and milestones. • Discussion of Business Considerations • Risk analysis. • What can go wrong? • What is your fall back plan?
