(理解怎样跟踪项目进展).ppt

2007/2008,Chapter 3,Planning and Managing the Project,Learning objectives,Understand how to track project progress. （理解怎样跟踪项目进展） Identify different communication styles of personnel and how these styles affect team organization. （描述不同人员的沟通方式和他们的沟通方式对项目组所产生的影响） Apply several effort and schedule estimation models. （应用部分结果和时间表进行项目预测） Identify risks and understand what is meant by risk management.（识别风险并理解什么是风险管理） Describe how process models and project management fit together.（描述怎样使过程模型与项目管理相吻合）,3.1 TRACKING PROGRESS,A typical project begins when a customer approaches you to discuss a perceived need. Usually customers have several questions to be answered. Do you understand my problem and my needs? Can you design a system that will solve my problem or satisfy my needs? How long will it take you to develop such a system? How much will it cost to have you develop such a system?,well-thought-out (慎重考虑后产生的) A project schedule,3.1 TRACKING PROGRESS,A project schedule describes the software development cycle for a particular project by enumerating(列举) the phases or stages of a project and breaking each into discrete tasks or activities to be done. The schedule also portrays(描绘；描写) the interactions(互相影响) among these activities and estimates(估计) the time that each task or activity will take. Thus, the schedule is a timeline(时间线) that shows when activities will begin and end, and when the related development products will be ready.,3.1 TRACKING PROGRESS,The customer expects to see during project development (to be deliverables ) . documents (文档) . demonstrations (论证,表示) of function . demonstrations of subsystems . demonstrations of accuracy(准确性) . demonstrations of reliability, security, or performance(可靠性、安全性或性能),3.1 TRACKING PROGRESS,A milestone is the completion of an activity-a particular point in time; A milestone is the end of a specially designated activity,3.1 TRACKING PROGRESS,Work Breakdown and Activity Graphs(工作分解与活动图) Analysis of this kind is sometimes described as generating a work breakdown structure (工作细分结构, 任务分解结构)for a given project, because it depicts the project as a set of discrete pieces of work.,3.1 TRACKING PROGRESS,Milestones in Building a House 1.1. Survey complete (完成测量) 1.2. Permits issued (执照已发行) 1.3. Excavation complete (完成挖掘) 1.4. Materials on hand (原料) 2.1. Foundation laid (打基础) 2.2. Outside walls complete(完成外墙) 2.3. Exterior plumbing complete(外部管道) 2.4. Exterior electrical work complete 2.5. Exterior siding (旁边的, 枝节的) complete 2.6. Exterior painting complete(外部粉刷) 2.7. Doors and fixtures mounted (外部门窗与设备安装) 2.8. Roof complete 3.l. Interior plumbing complete(内部管道) 3.2. Interior electrical work complete 3.3. wallboard in place(内墙) 3.4. Interior painting complete 3.5. Floor covering laid 3.6. Doors and fixtures mounted (内部门窗与设备安装),Example:,3.1 TRACKING PROGRESS,We can describe each activity with four parameters(参数): the precursor (预兆; 先兆), duration(持续时间), due date(到期日), and endpoint(终点). A precursor is an event or set of events that must occur before the activity can begin; it describes the set of conditions that allows the activity to begin. The duration is the length of time needed to complete the activity. The due date is the date by which the activity must be completed, frequently determined by contractual deadlines. Signifying(表示) that the activity has ended, The endpoint is usually a milestone or deliverable. We can illustrate(阐明) the relationships among activities by using these parameters. In particular, we can draw an activity graph to depict the dependencies(依赖关系), the nodes of the graph are the project milestones, and the lines linking the nodes represent the activities involved.,3.1 TRACKING PROGRESS,Estimating Completion(估计完成时间) Analyzing the paths among the milestones of a project in this way is called the Critical Path Method (CPM)( 关键路径方法), The paths can show us the minimum amount of time it will take to complete the project, given our estimates of each activitys duration(持续时间). Moreover, CPM reveals(展现，揭示) those activities that are most critical(临界值) to completing the project on time.,3.1 TRACKING PROGRESS,Slack time(富裕时间, 延缓时间) or float(浮动) for an activity is the difference between the available time and the real time for that activity Slack time = available time(可利用时间) real time Slack time = latest start time(最迟开始时间 ) - earliest start time(最早开始时间 ),3.1 TRACKING PROGRESS,The Program Evaluation and Review Technique (PERT) (统筹法, 统筹安排法) 计划评审技术,计划评审法) is a popular critical path analysis technique that assumes a normal distribution(正态分布). PERT determines the probability that the earliest start time for an activity is close to(接近于) the scheduled time for that activity using information such as probability distribution(概率分布), latest and earliest start times, and the activity graph, a PERT program can calculate(计算) the critical path and identify those activities most likely to be bottlenecks(瓶颈). Many project managers use the CPM or PERT method to examine their projects. However, these methods are valuable only for stable projects in which several activities take place concurrently（同时，并发）,3.1 TRACKING PROGRESS,Tools to Track Progress(跟踪进展的工具) : There are many tools that can be used to keep track of a projects progress. Some are manual(手册, 指南), others are simple spreadsheet applications(表格处理软件), and still others are sophisticated(完善) tools with complex graphics.,3.1 TRACKING PROGRESS,Tools to Track Progress(跟踪进展的工具) : Many project management software systems draw（提供） a work breakdown structure（详细结构） and also assist（帮助） the project manager in tracking progress by step（措施） and activity.,3.2 PROJECT PERSONNEL（项目组 ),To be continue.,Staff Roles and Characteristics（人员任务与特征）: However, not every task is performed by the same person or group; the assignment(指派，分配) of staff to tasks depends on project size, staff expertise, and staff experience. There is great advantage(有利条件) in assigning different responsibilities(责任, 职责) to different sets of people, offering “checks and balances“(制衡原则 ,制约与平衡原则) that can identify faults early in the development process.,3.2 PROJECT PERSONNEL（项目组 ),Project personnel may differ in many ways, and it is not enough to say that a project needs an analyst, two designers, and five programmers, for example. Two people with the same job title may differ in at least one of the following ways:,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),. ability to perform the work（完成工作的能力） . interest in the work（工作积极性） . experience with similar applications（工作经历） . experience with similar tools or languages(工具与软件应用能力) . experience with similar techniques（技术经历） . experience with similar development environment（开发环境的经历） . training（培训） . ability to communicate with others（与他人沟通的能力） . ability to share responsibility with others（承担责任的能力） . management skills（管理能力）,Each of these characteristics can affect an individuals ability to perform(执行) productively(有结果地).,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),The novelty of the work is sometimes a factor in generating interest in it. On the other hand, there are always people who prefer(更喜欢, 宁愿) doing what they know and do best, rather than venturing(好冒险的, 大胆的) into new territory(领域). It is important that whoever is chosen for a task be excited about performing it, no matter what the reason.,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),Given equal ability and interest, two people may still differ in the amount of experience(体验, 经历) or training they have had with similar applications, tools, or techniques. selection of project personnel involves not only individual ability and skill, but also experience and training.,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),On every software development or maintenance project, members of the development team communicate with one another, with users, and with the customer. The projects progress is affected not only by the degree of communication, but also by the ability of individuals to communicate their ideas.,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),Software failures can result from a breakdown in communication and understanding, so the number of people who need to communicate with one another can affect the quality of the resulting product.,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),In general, if a project has n workers, then there are n(n1)/2 pairs of people who might need to communicate, and 2n1 possible teams that can be created to work on smaller pieces of the project. Thus, a project involving only 10 people can use 45 lines of communication, and there are 1023 possible committees or teams that can be formed to handle(处理) subsystem development!,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),Many projects involve several people who must share responsibility for completing one or more activities. Those working on one aspect of project development must trust(信任, 信赖) other team members to do their parts. In classes, you are usually in total control of the projects you do.,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),You begin with the requirements (usually prescribed by your instructor), design a solution to the problem, outline the code, write the actual lines of code, and test the resulting programs.,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),However, when working in a team, either in school or for an employer or customer, you must be able to share the workload(工作量). Not only does this require verbal communication of ideas and results, but it also requires written documentation of what you plan to do and what you have done. You must accept the results of others without redoing their work. Many people have difficulty in sharing control in this way.,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),several aspects of a workers background can affect the quality of the project team. A project manager should know each persons interests and abilities when choosing who will work together.,3.2 PROJECT PERSONNEL（项目组 ),Work Styles(工作作风) Different people have different preferred(可取，较佳，优先选用) styles(设计风格) for interacting(相互作用的) with others on the job and with understanding problems that arise in the course of their work. Jung (1959) calls the former extroverts (性格外向的人)and the latter introverts(格性内向的人). Clearly your communication style affects the way you interact with others on a project. Similarly, intuitive(本能的,天生的) people base their decisions on feelings about and emotional(情绪的, 情感的) reactions to a problem. Others are rational(理性的), deciding primarily by examining the facts and carefully considering all options.,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),rational extroverts rational introverts intuitive extroverts intuitive extrovert ,3.2 PROJECT PERSONNEL（项目组 ),Project Organization . the backgrounds and work styles of the team members . the number of people on the team . the management styles of the customers and developers,To be continue.,3.2 PROJECT PERSONNEL（项目组 ),FIGURE 3.11 Chief programmer team organization,To be continue.,3.3 EFFORT ESTIMATION（工作量估计）,One of the crucial(至关紧要的) aspects of project planning and management is understanding how much the project is likely to cost. Cost overruns(超出限度) can cause customers to cancel projects, and cost underestimates(低估) can force a project team to invest(投资) much of its time without financial(财务的, 金融的) compensation(补偿).,To be continue.,The project budget(预算) pays for several types of costs: facilities(设备), staff(职员), methods, and tools. The facilities costs include hardware, space, furniture(家具), telephones, modems, heating and air conditioning(取暖装置), cables, disks, paper, pens, photocopiers(影印机), and all other items that provide the physical environment in which the developers will work.,3.3 EFFORT ESTIMATION（工作量估计）,To be continue.,There are sometimes hidden costs that are not apparent to the managers and developers. Other project costs involve purchasing(购买) software and tools to support development efforts. In addition to tools for designing and coding the system, the project may buy software to capture requirements, organize documentation, test the code, keep track of changes, generate test data, support group meetings, and more. These tools, sometimes called Computer-Aided Software Engineering (or CASE) tools, are sometimes required by the customer or as part of a companys standard software development process.,3.3 EFFORT ESTIMATION（工作量估计）,To be continue.,For most projects, the biggest component of cost is effort(工作量). We must determine how many staff-days of effort will be required to complete the project. Effort is certainly the cost component with the greatest degree of uncertainty we have seen how work style, project organization, ability, interest, experience, training, and other employee characteristics can affect the time it takes to complete a task. Moreover, when a group of workers must communicate and consult with one another, the effort needed is increased by the time required for meetings, documentation, and training.,3.3 EFFORT ESTIMATION（工作量估计）,To be continue.,Cost, schedule, and effort estimation must be done as early as possible during the projects life cycle, the estimate can be refined(精确的), based on more complete information about the projects characteristics,3.3 EFFORT ESTIMATION（工作量估计）,To be continue.,Expert Judgment（专家论证） Many effort-estimation methods rely on expert judgment. Some are informal techniques, based on a managers experience with similar projects. Thus, the accuracy(精确) of the prediction(预言) is based on the competence(能力), experience(经验), objectivity(客观性), and perception(洞察力) of the estimator(估价者).,3.3 EFFORT ESTIMATION（工作量估计）,top-down(自顶向下) or bottom-up(自底向上),To be continue.,The analogy process(模拟法,相似法) can be formalized(使正式, 形式化) by asking several experts to make three predictions(预测): a pessimistic(悲观的) one (x), an optimistic(乐观的) one (y), and a most likely(很可能(多半,大概) guess (z). Then our estimate is the mean of the beta probability distribution determined by these numbers: (x + 4y + z)/6. By using this technique, we produce an estimate that “normalizes(标准化，规范格化)“ the individual estimates.,3.3 EFFORT ESTIMATION（工作量估计）,To be continue.,In general, experiential(根据经验的) models, by relying(依赖, 依靠) mostly on expert judgment, are subject to all its inaccuracies(误差; 不精确, 不准确). They rely on the experts ability to determine which projects are similar and in what ways. However, projects that appear to be very similar can in fact be quite different.,3.3 EFFORT ESTIMATION（工作量估计）,To be continue.,Even when we know how one project differs from another, we do not always know how the differences affect the cost. A proportional strategy(比例策略) is unreliable(不可靠的), because project costs are not always linear Expert judgment suffers not only from variability(可变性) and subjectivity(主观性), but also from dependence on current data.,3.3 EFFORT ESTIMATION（工作量估计）,Algorithmic Methods（计算方法） Researchers have created models that express the relationship between effort and the factors that influence(影响, 改变) it. The models are usually described using equations, where effort is the dependent variable, and several factors (such as experience, size, and application type) are the independent variables(自变量). Most of these models acknowledge that project size is the most influential factor(影响因素) in this equation by expressing effort as,3.3 EFFORT ESTIMATION（工作量估计）,where S is the estimated size of the system, and a, b, and c are constants. X is a vector(矢量) of cost factors(成本因素), x1 through xn, and m is an adjustment(调整) multiplier(乘法器) based on these factors. In other words, the effort is determined mostly by the size of the proposed system, adjusted by the effects of several other project, process, product, or resource characteristics.,3.3 EFFORT ESTIMATION（工作量估计）,Walston and Felix (1977) developed one of the first models of this type, finding that IBM data from 60 projects yielded(产出, 产量) an equation of the form The projects that supplied data built systems with size ranging from 4000 to 467,000 lines of code, written in 28 different high-level languages on 66 computers, and representing from 12 to 11,758 person-months of effort. Size was measured as lines of code, including comments(注释) as long as they did not exceed(超出) 50 percent of the total lines in the program.,3.3 EFFORT ESTIMATION（工作量估计）,The basic equation was supplemented(补充) with a productivity(生产力) index that reflected(反射，反映) 29 factors that can affect productivity, shown in Table 3.7. Bailey and Basili (1981) suggested a modeling technique, called a meta-model(后模型), for building an estimation equation that reflects your own organizations characteristics. They demonstrated(证明) their technique using a database of 18 scientific projects written in Fortran at NASAs(美国)国家航空和宇宙航行局) Goddard Space Flight Center(戈达德宇航中心),3.3 EFFORT ESTIMATION（工作量估计）,First, they minimized the standard error estimate and produced an equation that was very accurate: Then, they adjusted(调整, 调节) this initial estimate based on the ratio of errors. If R is the ratio between the actual effort, E, and the predicted(预测) effort, E, then the effort adjustment(调整, 调节) is defined as,3.3 EFFORT ESTIMATION（工作量估计）,They then adjusted the initial(最初的,开始的) effort estimate E this way: Finally Bailey and Basili (1981) accounted for other factors that affect effort, shown in Table 3.8. For each entry in the table, the project is scored from 0 (not present) to 5 (very important), depending on the judgment of the project manager. Thus, the total score for METH(Method 方法) can be as high as(高达) 45, for CPLX(Complex 复合，成套) as high as 35, and for EXP(Expanded 扩展的,延长的)( Expect 期待,预期) as high as 25. Their model describes a procedure, based on multi-linear(多线性) least-square(少平方) regression(回归), for using these scores to further modify the effort estimate.,3.3 EFFORT ESTIMATION（工作量估计）,Clearly one of the problems with models of this type is their dependence on size as a key variable. Estimates are usually required early well before accurate size information is a