1、1,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Chapter 28,Risk Analysis,Slide Set to accompanySoftware Engineering: A Practitioners Approach, 7/e by Roger S. Pressman Slides copyright 1996, 200

2、1, 2005, 2009 by Roger S. Pressman For non-profit educational use only May be reproduced ONLY for student use at the university level when used in conjunction with Software Engineering: A Practitioners Approach, 7/e. Any other reproduction or use is prohibited without the express written permission

3、of the author. All copyright information MUST appear if these slides are posted on a website for student use.,2,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,第28章,風(fēng)險分析,幻燈片組陪Slide Set to accompany軟件工程: 一個從業(yè)者的方法, 7/e by Roger S. Pressman Slides copyright

4、1996, 2001, 2005, 2009 by Roger S. Pressman 僅用于非盈利教學(xué)使用 僅用于為大學(xué)生講解軟件工程課程時配套使用： 一個從業(yè)者的方法, 7/e. 未經(jīng)作者書面許可，禁止轉(zhuǎn)載使用 該幻燈片被放在網(wǎng)站上供學(xué)生使用時，必須標明所有的版權(quán)信息。,3,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Project

5、Risks,What can go wrong?,What is the likelihood?,What will the damage be?,What can we do about it?,4,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,項目風(fēng)險,有哪些可能出現(xiàn)的錯誤?,有多大的可能性?,將會造成什么損失?,我們可以做些什么?,5,These slides are designed to accompany Software Engineerin

6、g: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Reactive Risk Management,project team reacts to risks when they occur mitigationplan for additional resources in anticipation of fire fighting fix on failureresource are found and applied when the risk stri

7、kes crisis managementfailure does not respond to applied resources and project is in jeopardy,6,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,無風(fēng)險管理,風(fēng)險出現(xiàn)時項目團隊的做法 減少損失預(yù)計到問題時計劃額外的資源 聚焦失敗當風(fēng)險襲來時找到并采取對策 危機管理如果采取的對策無法規(guī)避失敗，項目將處于危險之中,7,These slides are designed

8、to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Proactive Risk Management,formal risk analysis is performed organization corrects the root causes of risk TQM concepts and statistical SQA examining risk sources that lie bey

9、ond the bounds of the software developing the skill to manage change,8,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,積極的風(fēng)險管理,進行正規(guī)的風(fēng)險分析 組織糾正風(fēng)險的根本原因 TQM（全面質(zhì)量管理）的理念和統(tǒng)計SQA（關(guān)鍵過程域） 研究風(fēng)險來源，超越軟件的界限謊言 提高能力來管理變革,9,These slides are designed to accompany Software E

10、ngineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Seven Principles,Maintain a global perspectiveview software risks within the context of system and the business problem Take a forward-looking viewthink about the risks that may arise in the future

11、; establish contingency plans Encourage open communicationif someone states a potential risk, dont discount it. Integratea consideration of risk must be integrated into the software process Emphasize a continuous processthe team must be vigilant throughout the software process, modifying identified

12、risks as more information is known and adding new ones as better insight is achieved. Develop a shared product visionif all stakeholders share the same vision of the software, it likely that better risk identification and assessment will occur. Encourage teamworkthe talents, skills and knowledge of

13、all stakeholder should be pooled,10,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,七項原則,保持一個全局的視角在系統(tǒng)和業(yè)務(wù)問題背景下考慮軟件的風(fēng)險 采取前瞻性的觀點考慮在未來會出現(xiàn)的風(fēng)險; 建立應(yīng)急預(yù)案 鼓勵開放式的溝通交流重視別人提出的潛在風(fēng)險 歸納整合對風(fēng)險的考慮必須納入軟件開發(fā)過程 強調(diào)一個連續(xù)的過程應(yīng)在綜合考慮已知的信息和能夠預(yù)見的新增加的風(fēng)險的情況下修改被確認的風(fēng)險，在整個軟件開發(fā)過程中團隊必須要對此保持警惕

14、制定一個共同的產(chǎn)品遠景規(guī)劃如果所有的利益相關(guān)者對于軟件擁有同樣的遠景規(guī)劃，將會有一個更好的風(fēng)險識別和評估 鼓勵團隊合作應(yīng)充分匯聚所有利益相關(guān)者的才智、技能和知識,11,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,RISK,Risk Management Paradigm,control,identify,analyze,plan,trac

15、k,12,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,RISK,風(fēng)險管理范例,控制,識別,分析,計劃,跟蹤k,13,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Risk Identification

16、,Product sizerisks associated with the overall size of the software to be built or modified. Business impactrisks associated with constraints imposed by management or the marketplace. Customer characteristicsrisks associated with the sophistication of the customer and the developers ability to commu

17、nicate with the customer in a timely manner. Process definitionrisks associated with the degree to which the software process has been defined and is followed by the development organization. Development environmentrisks associated with the availability and quality of the tools to be used to build t

18、he product. Technology to be builtrisks associated with the complexity of the system to be built and the newness of the technology that is packaged by the system. Staff size and experiencerisks associated with the overall technical and project experience of the software engineers who will do the wor

19、k.,14,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,風(fēng)險識別,產(chǎn)品規(guī)模風(fēng)險與要建立或修改的軟件的整體規(guī)模有關(guān)系. 業(yè)務(wù)影響風(fēng)險與強加在管理或市場的限制有關(guān)系. 客戶特點風(fēng)險與客戶的成熟和開發(fā)人員及時與客戶溝通的能力有關(guān)系. 過程定義風(fēng)險與軟件過程分析和開發(fā)部門遵循分析的程度有關(guān)系. 開發(fā)環(huán)境風(fēng)險與被用來建立產(chǎn)品的工具的可用性和質(zhì)量有關(guān)系. 掌握的技能風(fēng)險與要建立的系統(tǒng)的復(fù)雜性和用來封裝系統(tǒng)的“新穎”的技能有關(guān)系. 員工規(guī)模和經(jīng)驗風(fēng)險與要從事這項工作的

20、軟件工程師的整體技能和工程經(jīng)驗有關(guān)系.,15,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Assessing Project Risk-I,Have top software and customer managers formally committed to support the project? Are end-users ent

21、husiastically committed to the project and the system/product to be built? Are requirements fully understood by the software engineering team and their customers? Have customers been involved fully in the definition of requirements? Do end-users have realistic expectations?,16,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)

22、者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman. t 2009 by Roger Pressman.,評估項目風(fēng)險-I,高層的軟件和客戶經(jīng)理是否正式承諾支持該項目? 最終用戶是否積極致力于項目和系統(tǒng)/產(chǎn)品的興建？ 客戶是否充分參與需求分析? 最終用戶是否有切合實際的期望?,17,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Sli

23、des copyright 2009 by Roger Pressman.,Assessing Project Risk-II,Is project scope stable? Does the software engineering team have the right mix of skills? Are project requirements stable? Does the project team have experience with the technology to be implemented? Is the number of people on the proje

24、ct team adequate to do the job? Do all customer/user constituencies agree on the importance of the project and on the requirements for the system/product to be built?,18,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,評估項目風(fēng)險-II,項目范圍是否確定? 軟件工程師是否有需要的綜合技能?

25、項目需求是否確定? 項目團隊是否有實現(xiàn)這項技術(shù)的經(jīng)驗? 完成這項工作的項目團隊的人手是否充足? 所有的顧客/用戶群是否都同意項目的重要性和對要建立的系統(tǒng)/項目的需求分析?,19,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Risk Components,performance riskthe degree of uncertainty t

26、hat the product will meet its requirements and be fit for its intended use. cost riskthe degree of uncertainty that the project budget will be maintained. support riskthe degree of uncertainty that the resultant software will be easy to correct, adapt, and enhance. schedule riskthe degree of uncerta

27、inty that the project schedule will be maintained and that the product will be delivered on time.,20,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,風(fēng)險組成部分,履約風(fēng)險產(chǎn)品滿足需求和符合預(yù)期用途的不確定性的程度. 成本風(fēng)險需要保證的項目預(yù)算的不確定性的程度. 支持風(fēng)險軟件易于更改、調(diào)整和提高的不確定性的程度. 進度風(fēng)險項目進度保證和項目及時交付的不確定性的

28、程度.,21,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Risk Projection,Risk projection, also called risk estimation, attempts to rate each risk in two ways the likelihood or probability that the r

29、isk is real the consequences of the problems associated with the risk, should it occur. The are four risk projection steps: establish a scale that reflects the perceived likelihood of a risk delineate the consequences of the risk estimate the impact of the risk on the project and the product, note t

30、he overall accuracy of the risk projection so that there will be no misunderstandings.,22,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,風(fēng)險預(yù)測,風(fēng)險預(yù)測, 也被稱作風(fēng)險估計, 試圖從兩個方面對風(fēng)險進行評分 風(fēng)險存在的可能性和概率 風(fēng)險導(dǎo)致的問題的后果. 風(fēng)險預(yù)測的四個步驟: 建立能夠反映出可認知的可能風(fēng)險 劃定風(fēng)險的后果 估計風(fēng)險對項目和產(chǎn)品的影響 未避免誤區(qū)，應(yīng)注

31、意風(fēng)險預(yù)測的整體準確性.,23,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Building a Risk Table,Risk,Probability,Impact,RMMM,Risk Mitigation Monitoring & Management,24,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGra

32、w-Hill 2009). Slides copyright 2009 by Roger Pressman.,建立風(fēng)險表,風(fēng)險,概率,影響,風(fēng)險 緩解 監(jiān)視 管理,25,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Building the Risk Table,Estimate the probability of occurrence

33、Estimate the impact on the project on a scale of 1 to 5, where 1 = low impact on project success 5 = catastrophic impact on project success sort the table by probability and impact,26,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,構(gòu)建風(fēng)險表,估計發(fā)生的概率 用1到5來估計對項

34、目的影響程度 1 = 對項目成功影響較小 5 = 對項目成功有災(zāi)難性的影響 通過概率和影響對表格排序,27,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Risk Exposure (Impact),The overall risk exposure, RE, is determined using the following relati

35、onship Hal98: RE = P x C where P is the probability of occurrence for a risk, and C is the cost to the project should the risk occur.,28,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,風(fēng)險暴露 (影響),整體的風(fēng)險暴露, RE, 使用以下表達式 Hal98: RE = P x C where P代表風(fēng)險出現(xiàn)的概率 C 代表

36、發(fā)生風(fēng)險時產(chǎn)生的項目成本.,29,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Risk Exposure Example,Risk identification. Only 70 percent of the software components scheduled for reuse will, in fact, be integra

37、ted into the application. The remaining functionality will have to be custom developed. Risk probability. 80% (likely). Risk impact. 60 reusable software components were planned. If only 70 percent can be used, 18 components would have to be developed from scratch (in addition to other custom softwa

38、re that has been scheduled for development). Since the average component is 100 LOC and local data indicate that the software engineering cost for each LOC is $14.00, the overall cost (impact) to develop the components would be 18 x 100 x 14 = $25,200. Risk exposure. RE = 0.80 x 25,200 $20,200.,30,該

39、幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,風(fēng)險暴露舉例,風(fēng)險識別. 實際上只有70%的計劃復(fù)用的軟件組件被集成到應(yīng)用程序. 其余的功能將不得不定制開發(fā). 風(fēng)險概率. 80% (可能). 風(fēng)險影響. 計劃60個可復(fù)用軟件組件. 如果只有70%可以使用，那么18個組件都將必須從頭開發(fā)(除了其他已計劃定制開發(fā)的軟件以外). 由于平均組件是100LOC，而且本地數(shù)據(jù)顯示本項目的成本是每個LOC14美元，開發(fā)這些組件的全部成本（影響）將是25200美元（18 x

40、100 x 14 = $25,200）. 風(fēng)險曝光. RE = 0.80 x 25,200 $20,200.,31,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,mitigationhow can we avoid the risk? monitoringwhat factors can we track that will enable

41、us to determine if the risk is becoming more or less likely? managementwhat contingency plans do we have if the risk becomes a reality?,Risk Mitigation, Monitoring,and Management,32,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,緩解如何才能避免風(fēng)險? 監(jiān)控跟蹤哪些因素可以是我們

42、判斷出風(fēng)險是可能降低還是增加? 管理如果風(fēng)險真的出現(xiàn)，我們有什么應(yīng)對的措施?,風(fēng)險緩解，監(jiān)控和管理,33,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Risk Due to Product Size, estimated size of the product in LOC or FP?, estimated size of produc

43、t in number of programs,files, transactions?, percentage deviation in size of product from,average for previous products?, size of database created or used by the product?, number of users of the product?, number of projected changes to the requirements,for the product? before delivery? after delive

44、ry?, amount of reused software?,Attributes that affect risk:,34,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,產(chǎn)品規(guī)模引起的風(fēng)險, 估計產(chǎn)品的規(guī)模在LOC or FP?, 從方案、文件、交易的數(shù)量估計產(chǎn)品的規(guī)模？, 從之前產(chǎn)品的平均值估計產(chǎn)品規(guī)模的誤差百分比？, 產(chǎn)品創(chuàng)建或使用的數(shù)據(jù)庫的大小?, 產(chǎn)品的用戶數(shù)量?, 產(chǎn)品預(yù)期的需求變化的數(shù)量？交付前？交付后？, 軟件的復(fù)用量?,影響風(fēng)險的屬性:

45、,35,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Risk Due to Business Impact, affect of this product on company revenue?, visibility of this product by senior management?, reasonableness of del

46、ivery deadline?, number of customers who will use this product, interoperability constraints, sophistication of end users?, amount and quality of product documentation that,must be produced and delivered to the customer?, governmental constraints, costs associated with late delivery?, costs associat

47、ed with a defective product?,Attributes that affect risk:,36,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,業(yè)務(wù)影響引起的風(fēng)險, 產(chǎn)品對公司收入的影響?, 高層對產(chǎn)品的預(yù)期?, 合理的交貨期限?, 使用此產(chǎn)品的客戶數(shù)量?, 互用性的限制?, 最終用戶的熟練度?, 必須制作并交付客戶的產(chǎn)品文件的數(shù)量和質(zhì)量?, 政府限制？, 推遲交貨的費用?, 由于產(chǎn)品缺陷造成的相關(guān)費用?,影響風(fēng)險的屬性:,37,T

48、hese slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Risks Due to the Customer, Have you worked with the customer in the past?, Does the customer have a solid idea of requirements?, Has the customer agr

49、eed to spend time with you?, Is the customer willing to participate in reviews?, Is the customer technically sophisticated?, Is the customer willing to let your people do their,jobthat is, will the customer resist looking over your,shoulder during technically detailed work?, Does the customer unders

50、tand the software,engineering process?,Questions that must be answered:,38,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,用戶原因引起的風(fēng)險, 之前是否和用戶合作過?, 用戶對需求有一個固定的想法?, 用戶是否愿意花時間和你一起討論?, 客戶是否愿意參與評論?, 客戶的技術(shù)是否是熟練的?, 客戶是否愿意你的團隊做這個項目也就是客戶是否 對技術(shù)細節(jié)工作不屑一顧?, 客戶是否了解軟件工程

51、過程?,必須解決的問題:,39,These slides are designed to accompany Software Engineering: A Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Risks Due to Process Maturity, Have you established a common process framework?, Is it followed by project teams?, Do you have manag

52、ement support for software engineering, Do you have a proactive approach to SQA?, Do you conduct formal technical reviews?, Are CASE tools used for analysis, design and,testing?, Are the tools integrated with one another?, Have document formats been established?,Questions that must be answered:,40,該

53、幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,工藝成熟度引起的風(fēng)險, 是否已建立了一個通用的過程框架?, 項目團隊是否遵守它?, 軟件工程是否有管理方面的支持, 對SQA有一個積極地態(tài)度?, 是否進行了正式的技術(shù)評審?, 是否用CASE工具進行分析，設(shè)計和測試?, 工具是否與另一個集成?, 是否文件格式已確立?,必須解決的問題:,41,These slides are designed to accompany Software Engineering: A

54、 Practitioners Approach, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,Technology Risks, Is the technology new to your organization?, Are new algorithms, I/O technology required?, Is new or unproven hardware involved?, Does the application interface with new software?, Is a specia

55、lized user interface required?, Is the application radically different?, Are you using new software engineering methods?, Are you using unconventional software development,methods, such as formal methods, AI-based approaches,artificial neural networks?, Are there significant performance constraints?

56、, Is there doubt the functionality requested is do-able?,Questions that must be answered:,42,該幻燈片用于配合軟件工程課程使用： 一個從業(yè)者的方法, 7/e (McGraw-Hill 2009). Slides copyright 2009 by Roger Pressman.,技術(shù)風(fēng)險, 這種技術(shù)對你的團隊是否是新的?, 是否需要新的算法，I/O技術(shù)?, 是否有新的或未經(jīng)驗證的硬件?, 是否有新的軟件程序接口?, 是否需要專門的用戶界面?, 是否應(yīng)用程序完全不同?, 是否使用了新的軟件工程方法?, 是否使用非傳統(tǒng)的軟件開發(fā)方法