1、Requirements DiscoveryChapter 3System Analysis & Design Copyright College of Software, BUAAContents1. Requirements2. Process of Requirements Discovery23. Fact-Finding Techniques for Requirements DiscoverySystem Analysis & Design Copyright College of Software, BUAAContents1. Requirements2. Process of

2、 Requirements Discovery33. Fact-Finding Techniques for Requirements DiscoverySystem Analysis & DesignCopyright College of Software, BUAA-4-RequirementsSystem requirementsomething that the information system must do or a property that it must have. Requirements discoverythe process and techniques use

3、d by systems analysts to identify or extract system problems and solution requirements from the user community. System Analysis & DesignCopyright College of Software, BUAA-5-Functional vs. Nonfunctional RequirementsFunctional requirementsomething the information system must doNonfunctional requireme

4、nt (PIECES)a property or quality the system must havePerformanceInformationEconomyControl (and Security) EfficiencyServiceSee also P146, Table 6-1System Analysis & DesignCopyright College of Software, BUAA-6-Results of Incorrect RequirementsThe system may cost more than projected.The system may be d

5、elivered later than promised.The system may not meet the users expectations and they may not to use it.Once in production, costs of maintaining and enhancing system may be excessively high.The system may be unreliable and prone to errors and downtime.Reputation of IT staff is tarnished as failure wi

6、ll be perceived as a mistake by the team.System Analysis & DesignCopyright College of Software, BUAA-7-Relative Cost to Fix an ErrorSystem Analysis & DesignCopyright College of Software, BUAA-8-Criteria for System RequirementsConsistentnot conflicting or ambiguous.Completedescribe all possible syste

7、m inputs and responses.Feasiblecan be satisfied based on the available resources and constraints.Requiredtruly needed and fulfill the purpose of the system.Accuratestated correctly.Traceabledirectly map to functions and features of system.Verifiabledefined so can be demonstrated during testing.Syste

8、m Analysis & Design Copyright College of Software, BUAAContents1. Requirements2. Process of Requirements Discovery93. Fact-Finding Techniques for Requirements DiscoveryProcess of Requirements DiscoveryProblem discovery and analysis Requirements discovery Documenting and analyzing requirements Requir

9、ements management System Analysis & Design Copyright College of Software, BUAA10Problem discovery and analysis Ishikawa DiagramGraphical tool used to identify, explore, and depict problems and the causes and effects of those problems. It is often referred to as a cause-and-effect diagram or a fishbo

10、ne diagram.Problem at right (fish head)Possible causes drawn as bones off main backboneBrainstorm for 3-6 main categories of possible causesSystem Analysis & Design Copyright College of Software, BUAA11Requirements DiscoveryGiven an understand of problems, the systems analyst can start to define req

11、uirements.Fact-findingthe formal process of using research, meetings, interviews, questionnaires, sampling, and other techniques to collect information about system problems, requirements, and preferencesIt is also called information gathering or data collection.System Analysis & Design Copyright Co

12、llege of Software, BUAA12Requirements Definition DocumentRequirements Definition DocumentA formal document that communicates the requirements of a proposed system to key stakeholders and serves as a contract for the systems project. Synonyms Requirements specificationRequirements definition reportRe

13、quirements statementFunctional specificationsSystem Analysis & Design Copyright College of Software, BUAA13Requirements ManagementRequirements management - the process of managing change to the requirementsOver the lifetime of the project it is very common for new requirements to emerge and existing

14、 requirements to changeStudies have shown that over the life of a project as much as 50 percent or more of the requirements will change before the system is put into productionSystem Analysis & Design Copyright College of Software, BUAA14System Analysis & Design Copyright College of Software, BUAACo

15、ntents1. Requirements2. Process of Requirements Discovery153. Fact-Finding Techniques for Requirements DiscoverySystem Analysis & DesignCopyright College of Software, BUAA-16-Fact-Finding EthicsFact-Finding often brings systems analysts into contact with sensitive information.Company plans, Employee

16、 salaries or medical historyCustomer credit card, social security, or other informationEthical behavior, Systems analysts mustnot misuse tect information from people who would misuse it.OtherwiseSystems analyst loses respect, credibility, and confidence of users and management, impair

17、ing ability to do jobOrganization and systems analyst could have legal liabilitySystem Analysis & DesignCopyright College of Software, BUAA-17-Seven Fact-Finding MethodsSampling of existing documentation, forms, and databases. Research and site visits. Observation of the work environment. Questionna

18、ires. Interviews. Prototyping. Joint requirements planning (JRP). System Analysis & DesignCopyright College of Software, BUAA-18-Sampling Existing Documentation, Forms, & FilesSampling process of collecting a representative sample of documents, forms, and records. Organization chartMemos and other d

19、ocuments that describe the problemStandard operating procedures for current systemCompleted formsManual and computerized screens and reportsSamples of databasesFlowcharts and other system documentationAnd moreSystem Analysis & DesignCopyright College of Software, BUAA-19-Things to be Gleaned from Do

20、cumentsSymptoms and causes of problemsPersons in organization who have understanding of problemBusiness functions that support the present systemType of data to be collected and reported by the systemQuestions that need to be covered in interviewsSystem Analysis & DesignCopyright College of Software

21、, BUAA-20-Why to Sample Completed Rather than Blank Forms Can determine type of data going into each blankCan determine size of data going into each blankCan determine which blanks are not used or not always usedCan see data relationshipsSystem Analysis & DesignCopyright College of Software, BUAA-21

22、-Sampling TechniquesRandomizationa sampling technique characterized by having no predetermined pattern or plan for selecting sample data. Stratificationa systematic sampling technique that attempts to reduce the variance of the estimates by spreading out the samplingfor example, choosing documents o

23、r records by formulaand by avoiding very high or low estimates. System Analysis & DesignCopyright College of Software, BUAA-22-ObservationUserObserverSystem Analysis & DesignCopyright College of Software, BUAA-23-ObservationObservationa fact-finding technique wherein the systems analyst either parti

24、cipates in or watches a person perform activities to learn about the system. Work samplinga fact-finding technique that involves a large number of observations taken at random intervals. System Analysis & DesignCopyright College of Software, BUAA-24-Collecting Facts by Observing People at WorkEven w

25、ith a well-conceived observation plan, the systems analyst is not assured that fact-finding will be successfulP152, The Railroad ParadoxThe lessons learned from the story:It is necessary to use the appropriate fact-finding technique for the problem at hand.Verify fact-finding results with users.Syst

26、em Analysis & DesignCopyright College of Software, BUAA-25-ObservationData gathered can be very reliableCan see exactly what is being done in complex tasksRelatively inexpensive compared with other techniquesCan do work measurementsPeople may perform differently when being observedWork observed may

27、not be representative of normal conditionsTiming can be inconvenientInterruptionsSome tasks not always performed the same wayMay observe wrong way of doing thingsAdvantagesDisadvantagesSystem Analysis & DesignCopyright College of Software, BUAA-26-Observation GuidelinesDetermine the who, what, where

28、, when, why, and how of the observation.Obtain permission from appropriate supervisors.Inform those who will be observed of the purpose of the observation.Keep a low profile.Take notes.Review observation notes with appropriate individuals.Dont interrupt the individuals at work.Dont focus heavily on

29、trivial activities.Dont make assumptions.System Analysis & DesignCopyright College of Software, BUAA-27-QuestionnairesQuestionnairea special-purpose document that allows the analyst to collect information and opinions from respondents. Free-format questionnairea questionnaire designed to offer the r

30、espondent greater latitude in the answer.A question is asked, and the respondent records the answer in the space provided after the question. Fixed-format questionnairea questionnaire containing questions that require selecting an answer from predefined available responses. Types of Fixed-Format Que

31、stionsMultiple-choice questions Rating questionsRanking questionsSystem Analysis & Design Copyright College of Software, BUAA28Rank the following transactions according to the amount of time you spend processing them._ % new customer orders_ % order cancellations_ % order modifications_ % paymentsTh

32、e implementation of quality discounts would cause an increase in customer orders. _ Strongly agree_ Agree_ No opinion_ Disagree_ Strongly disagreeIs the current accounts receivable report that you receive useful? _ Yes _ NoDeveloping a QuestionnaireDetermine what facts and opinions must be collected

33、 and from whom you should get themBased on the facts and opinions sought, determine whether free- or fixed-format questions will produce the best answersWrite the questionsTest the questions on a small sample of respondentsDuplicate and distribute the questionnaireSystem Analysis & Design Copyright

34、College of Software, BUAA29System Analysis & DesignCopyright College of Software, BUAA-30-QuestionnairesOften can be answered quicklyPeople can complete at their convenienceRelatively inexpensive way to gather data from a large numberAllow for anonymityResponses can be tabulated quicklyReturn rate i

35、s often lowNo guarantee that an individual will answer all questionsNo opportunity to reword or explain misunderstood questionsCannot observe body languageDifficult to prepareAdvantagesDisadvantagesSystem Analysis & DesignCopyright College of Software, BUAA-31-Developing a Questionnaire1. Determine

36、what facts and opinions must be collected and from whom you should get them. 2. Based on the facts and opinions sought, determine whether free- or fixed-format questions will produce the best answers. 3. Write the questions. 4. Test the questions on a small sample of respondents. 5. Duplicate and di

37、stribute the questionnaire. System Analysis & DesignCopyright College of Software, BUAA-32-InterviewsInterviewa fact-finding technique whereby the systems analysts collect information from individuals through face-to-face interaction. ObjectiveFind factsVerify factsClarify factsGenerate enthusiasmGe

38、t the end-user involvedIdentify requirementsSolicit ideas and opinionsSystem Analysis & DesignCopyright College of Software, BUAA-33-Roles in InterviewsInterviewer: Systems analystResponsible for organizing and conducting the interviewInterviewee: The system user or ownerIs asked to respond to a ser

39、ies of questionsQuestionSystem Analysis & DesignCopyright College of Software, BUAA-34-Types of Interviews and QuestionsUnstructured interviewconducted with only a general goal or subject in mind and with few, if any, specific questions. The interviewer counts on the interviewee to provide a framewo

40、rk and direct the conversation. Structured interviewinterviewer has a specific set of questions to ask of the interviewee. Open-ended questionquestion that allows the interviewee to respond in any way. Closed-ended questiona question that restricts answers to either specific choices or short, direct

41、 responses. System Analysis & DesignCopyright College of Software, BUAA-35-InterviewsGive analyst opportunity to motivate interviewee to respond freely and openlyAllow analyst to probe for more feedbackPermit analyst to adapt or reword questions for each individualCan observe nonverbal communication

42、Time-consumingSuccess highly dependent on analysts human relations skillsMay be impractical due to location of intervieweesAdvantagesDisadvantagesSystem Analysis & DesignCopyright College of Software, BUAA-36-Procedure to Conduct an InterviewSelect IntervieweesEnd usersLearn about individual prior t

43、o the interviewPrepare for the Interviewinterview guideConduct the InterviewSummarize the problemOffer an incentive for participationAsk the interviewee for assistanceFollow Up on the InterviewMemo that summarizes the interviewSystem Analysis & DesignCopyright College of Software, BUAA-37-Sample Int

44、erview GuideSystem Analysis & DesignCopyright College of Software, BUAA-38-Prepare for the InterviewTypes of Questions to AvoidLoaded questionsLeading questionsBiased questionsInterview Question GuidelinesUse clear and concise language. Dont include your opinion as part of the question. Avoid long o

45、r complex questions. Avoid threatening questions. Dont use “you” when you mean a group of people.System Analysis & DesignCopyright College of Software, BUAA-39-Conduct the InterviewDress to match intervieweeArrive on time Or early if need to confirm room setupOpen interview by thanking intervieweeSt

46、ate purpose and length of interview and how data will be usedMonitor the timeAsk follow-up questionsProbe until you understandAsk about exception conditions (what if.)System Analysis & DesignCopyright College of Software, BUAA-40-Interviewing Dos and DontsDress appropriatelyBe courteousListen carefu

47、llyMaintain control of the interviewProbeObserve mannerisms and nonverbal communicationBe patientKeep interviewee at easeMaintain self-controlFinish on timeAssume an answer is finished or leading nowhereReveal verbal and nonverbal cluesUse jargonReveal personal biasesTalk more than listenAssume anyt

48、hing about the topic or the intervieweeTape record (take notes instead)DoDontSystem Analysis & DesignCopyright College of Software, BUAA-41-Body Language and ProxemicsBody language the nonverbal information we communicate. Facial disclosureEye contactPostureProxemics the relationship between people

49、and the space around them. Intimate zonecloser than 1.5 feetPersonal zonefrom 1.5 feet to 4 feetSocial zonefrom 4 feet to 12 feetPublic zonebeyond 12 feetSystem Analysis & DesignCopyright College of Software, BUAA-42-Discovery PrototypingDiscovery prototyping the act of building a small-scale, repre

50、sentative or working model of the users requirements in order to discover or verify those requirements. System Analysis & DesignCopyright College of Software, BUAA-43-Discovery PrototypingCan experiment to develop understanding of how system might workAids in determining feasibility and usefulness o

51、f system before developmentServes as training mechanismAids in building test plans and scenariosMay minimize time spent on fact-findingDevelopers may need to be trained in prototypingUsers may develop unrealistic expectationsCould extend development scheduleAdvantagesDisadvantagesSystem Analysis & D

52、esignCopyright College of Software, BUAA-44-Joint Requirements PlanningJoint requirements planning (JRP) a process whereby highly structured group meetings are conducted for the purpose of analyzing problems and defining requirements. JRP is a subset of a more comprehensive joint application develop

53、ment or JAD technique that encompasses the entire systems development process.System Analysis & DesignCopyright College of Software, BUAA-45-JRP ParticipantsSponsorA single person, is an individual who is in top management.FacilitatorA single individual for leading all sessions that are held for a s

54、ystems project.Users and ManagersThe business knowledge to contributeScribesResponsible for keeping records pertaining to everything discussed in the meeting.IT StaffListen and take notes regarding issues and requirements voiced by the users and managersSystem Analysis & DesignCopyright College of S

55、oftware, BUAA-46-Steps to Plan a JRP Session1. Selecting a locationAway from workplace when possibleRequires several roomsEquipped with tables, chairs, whiteboard, overhead projectorsNeeded computer equipment2. Selecting the participantsEach needs release from regular duties3. Preparing the agendaBr

56、iefing documentationAgenda distributed before each sessionSystem Analysis & DesignCopyright College of Software, BUAA-47-Typical Room Layout for JRP sessionSystem Analysis & DesignCopyright College of Software, BUAA-48-BrainstormingSometimes, one of the goals of a JRP session is to generate possible

57、 ideas to solve a problem. Brainstorming is a common approach that is used for this purpose. Brainstorminga technique for generating ideas by encouraging participants to offer as many ideas as possible in a short period of time without any analysis until all the ideas have been exhausted. System Analysis & Desi