Chapter 4 Project Time Management PDF

Chapter 4 Project Time Management What’s Coming Ahead… Project Time Management: Big Picture Defining Activities Sequencing Activities Estimating Activity Resource Requirements Estimating Activity Duration Developing the Project Schedule Controlling Schedule Introduction At its core, a project consis...

Chapter 4 Project Time Management What’s Coming Ahead… Project Time Management: Big Picture Defining Activities Sequencing Activities Estimating Activity Resource Requirements Estimating Activity Duration Developing the Project Schedule Controlling Schedule Introduction At its core, a project consists of two main components: the project work that needs to be performed and the schedule to perform that work. As you learned in the previous chapter, the overall project work (scope) is broken down into smaller manageable components. These components in the WBS are called work packages. However, a work package might not be a suitable item to assign to an individual to perform. So, work packages can be rearranged, such as decomposed into smaller components called activities. A project schedule contains not only the activities to be performed, but also the order (sequence) in which the activities will be performed and a start and a finish date. The sequencing of activities is constrained by the dependencies among the activities. A realistic project schedule can be created from the bottom up by identifying the activities, estimating the resources for the activities, and determining the time that each activity will take with the given resources available. Once developed and approved, the schedule needs to be controlled to stay on track. All these tasks belong to what is called project time management. So, the main issue in this chapter is time management. To enable you to wrap your mind around this issue, I will explore the following three avenues: generating the data about project activities, such as determining activities and their characteristics, including resource requirements and activity durations; building a project schedule from the data on the activities; and controlling the schedule. Project Time Management: Big Picture Planning and controlling the project schedule is all about time management. To complete a project, you need to perform some activities to produce the project deliverables. To make that happen, you need to assign resources to the activities and schedule them. But before all this can happen, you need to identify the activities. Although all this sounds like common sense, it makes sense to define the following terms so we are all on the same page. ◆ Activity. Any task, such as a component of project work. ◆ Activity duration. The time measured in calendar units between the start and finish of a schedule activity. ◆ Schedule activity. A scheduled task (component of work) performed during the lifecycle of a project. Schedule activities are also referred to as just activities for brevity. ◆ Logical relationship. A dependency between two project schedule activities or between a schedule activity and a schedule milestone. Project Time Management: Big Picture 131 ◆ Schedule milestone. A milestone is a significant point (or event) in the life of a project, and a schedule milestone is a milestone on the project schedule. A milestone refers to the completion of an activity, marking possibly the completion of a set of activities, and therefore has zero duration. The completion of a major deliverable is an example of a milestone. Project time management includes the processes required to complete the project in a timely manner. Figure 4.1 presents the flow diagram for the time management processes that lead to schedule development. FIGURE 4.1 The time management processes that lead to schedule development. 132 Chapter 4 PROJECT TIME MANAGEMENT The usages of these processes are listed here: ◆ Define Activities. Identifies the specific schedule activities that must be performed to produce the project deliverables. ◆ Sequence Activities. Identifies the dependencies among the schedule activities and orders the activities accordingly. ◆ Estimate Activity Resources. Estimates the types and amounts of resources that will be required to perform each schedule activity. Examples of resources are material, equipment, supplies, and people. ◆ Estimate Activity Duration. Estimates the time in work periods individually for each schedule activity required for the activity’s completion. A work period is a measurement of time when the work is in progress; it is measured in hours, days, or months, depending upon the size of the activity. This estimate is performed for given resources. ◆ Develop Schedule. Develops the project schedule by analyzing schedule activity sequences, schedule activity durations, resource requirements, and schedule constraints. ◆ Control Schedule. Monitors the status of the project progress and controls the changes to the schedule baseline. These processes are listed in Table 4.1 with the major output from each process. Table 4.1 Processes of Scope Management Mapped to the Process Groups Time Management Process Process Group Major Output Define Activities Planning Activity list Sequence Activities Planning Project schedule network diagrams Estimate Activity Resources Planning Activity resource requirements Estimate Activity Durations Planning Activity duration estimates Develop Schedule Planning Project schedule Control Schedule Monitoring and controlling Work performance measurements Defining Activities 133 NOTE The underlying philosophy of project management for schedule development is to first develop the schedule based on the work required to complete the project tasks and then see how you can make it conform to other constraints, calendar requirements, and strategic goals of the organization. You, the project manager, build the schedule through cold, hard mathematical analysis, and you don’t just accept whatever schedule goals come down the pipeline from elsewhere, such as from the customer or the project sponsor. In a nutshell, the path to schedule development includes defining activities, arranging the activities in the correct order, and estimating the resources required to complete the activities. In other words, the work necessary for completing the project is expressed in terms of activities, and the resources are required to complete those activities. So, the first step toward schedule planning after creating the WBS is defining activities. Defining Activities Activities that need to be performed to produce the project deliverables are identified using the activity definition process shown in Figure 4.2. The starting point for defining the activities is the lowest level of the WBS that contains work packages. Each work package can be broken down into one or more activities. FIGURE 4.2 The Define Activities process: input, tools and techniques, and output. So, the key input items to the activity definition process are the WBS and the WBS dictionary. 134 Chapter 4 PROJECT TIME MANAGEMENT Input to Defining Activities Identifying project activities starts with the work packages in the WBS, which in turn are derived from the project scope statement. These two obvious input items, along with others, are discussed here. Project scope baseline. Elements of the scope baseline, such as deliverables, assumptions, and constraints, will be useful in defining activities. All the following three components of the project scope baseline are needed to define activities: ◆ WBS and WBS dictionary. The work packages in the WBS are decomposed into project activities. To define activities in detail so that you can assign appropriate resources to them, you need the details about work packages, which are provided in the WBS dictionary. ◆ Project scope statement. The WBS is built from the project scope statement. While dealing with the WBS, you might need to go back to the project scope statement. The following elements of the project scope statement are especially important to consider while identifying activities: ◆ Assumptions related to the activities or schedule planning, such as work hours per week ◆ Constraints that will limit the schedule options, such as predetermined deadlines on project milestones ◆ Project deliverables, to ensure that everything is covered in WBS work packages ◆ Enterprise environmental factors. The enterprise environmental factors relevant to identifying schedule activities include project management information systems and project scheduling software tools. ◆ Organizational process assets. Following are examples of organizational process assets that can be useful in the process of identifying activities: ◆ Organizational policies related to activity planning ◆ Organizational procedures and guidelines used in defining activities ◆ Knowledge base of lessons learned from previous projects regarding activity lists So, the major input to the activity definition process is the WBS, whose work packages are decomposed into activities using some tools and techniques discussed in the following section. Tools and Techniques for Defining Activities The major task in the Define Activities process is to decompose the work packages in the WBS into activities. This decomposition, along with other tools and techniques, is discussed here. Decomposition. Recall that you used the decomposition technique to create the WBS by subdividing the project deliverables into smaller manageable tasks or work components called work packages. Decomposition is also used in the activity definition process for subdividing the work packages into smaller, more manageable components called schedule activities. Defining Activities 135 TIP You create the WBS and decompose the work packages to project activities with the help of the project team. Even though the schedule is not yet developed and the resources are not fully assigned, the project team in some initial form will be there. When decomposing a work package into activities, involve the individuals who either are familiar with the work packages or will be responsible for them. Component planning. If there are areas of the project scope for which sufficient information is not available yet, there will definitely be corresponding components in the WBS that are not decomposed to the level of work packages. You can only develop a high-level schedule for these planning components. You accommodate this kind of high-level scheduling by using a technique called rolling wave planning to plan the project work at various levels of detail depending upon the availability of information. Work to be performed in the near future is planned to the low level of the WBS, whereas work to be performed far into the future can be planned at the relatively high level of the WBS. So, a WBS component at the bottom level of a branch of WBS hierarchy for which some planning can be performed is called a planning component. NOTE Rolling wave planning is an example of progressive elaboration, which was discussed in Chapter 1. Templates. As a timesaver and a guide, you can use a standard activity list or an activity list from a previous project similar to the project at hand as a template. The template can also contain information about the activities in it, such as required hours of effort. Expert judgment. Activities make the core of a project. So, it’s very important to identify and define them correctly to make the project schedule efficient and effective. Therefore, expert judgment is a very important tool that can be used in this process. For example, during the process of decomposing the work packages into schedule activities, you can use the help of team members and other experts who are experienced in developing WBS and project schedules. Using these techniques, you convert the work packages in the WBS into schedule activities, which, along with some other items, make the output of the activity definition process. Output of Defining Activities The key output item of the activity definition process is a comprehensive list of all the schedule activities that need to be performed to produce the project deliverables. This and other output items are discussed in the following list. 136 Chapter 4 PROJECT TIME MANAGEMENT Activity list. This is a list of all the activities that are necessary and sufficient to produce the project deliverables. In other words, these activities are derived from the WBS and hence are within the scope of the project. Also, the scope of each schedule activity should be described to sufficient detail in concrete terms, so that the team member responsible for it will understand what work needs to be performed. Examples of schedule activities include writing a chapter of a book, developing a computer program that will accomplish a well-defined purpose, and installing an application on a computer. Activity attributes. These attributes are in addition to the scope description of the activity in the activity list. The list of attributes of an activity can include the following: ◆ Activity identifier and code ◆ Activity description ◆ Assumptions and constraints related to this activity, such as imposed date ◆ Predecessor and successor activities ◆ Resource requirements ◆ Team member responsible for performing the work and information about the work—for example, where it will be performed Some attributes evolve over time. The attributes are used to arrange the activities in the correct order (sequencing) and to schedule them. Milestone list. A schedule milestone is a significant event in the project schedule, such as the completion of a major deliverable. A milestone can be mandatory, such as one required by a contract, or optional, such as one determined by the team to run the project more smoothly. The milestone list includes all the milestones and specifies whether a milestone is mandatory or optional. Milestones are used in building the schedule. CAUTION The Define Activities process generates the final output as activities and not deliverables. Therefore, ideally speaking, the WBS and the WBS dictionary should be generated before defining activities. However, practically speaking, the activity list, the WBS, and the WBS dictionary can be developed concurrently. To summarize, the output items of the activity definition process are a schedule activity list, a list of attributes for each activity, and a list of milestones. Before you can schedule them, the identified activities need to be arranged in the correct order, which is called sequencing. Sequencing Activities 137 Sequencing Activities The activity sequencing process is used to arrange the schedule activities in the appropriate order, which takes into account the dependencies among the activities. For example, if Activity B depends upon the product of Activity A, then Activity A must be performed before Activity B. So activity sequencing has a two-pronged goal—to identify the dependencies among the schedule activities and to order the activities accordingly. Figure 4.3 shows the activity sequencing process. FIGURE 4.3 The Sequence Activities process: input, tools and techniques, and output. Comparing Figure 4.3 to Figure 4.2 reveals that all the output items of the activity definition process are the input into the activity sequencing process, along with some other inputs. For example, the project scope statement is an additional input item, and it can be used as a source to check the accuracy of the activity list and to ensure that the activity list covers the scope of the project and the products. You use the appropriate tools and techniques to determine the dependencies among the schedule activities and sequence them accordingly. Tools and Techniques for Sequencing Activities Dependency determination is the prerequisite to determine sequencing. Therefore, most of the tools and techniques used for sequencing are focused on determining and displaying dependencies. Determining dependencies. To properly sequence the schedule activities, you need to determine the dependencies among them. As illustrated in Figure 4.4, a dependency relationship between two activities is defined by two terms: predecessor and successor. In other words, when two activities are in a dependency relationship with each other, one of them is a predecessor of the other, and the other one is the successor. In Figure 4.4, Activity A is a predecessor of Activity B, and Activity B is a successor of Activity A. That means A must start before B. 138 Chapter 4 PROJECT TIME MANAGEMENT FIGURE 4.4 Predecessor/successor relationship between two activities. By definition, the successor activity must start after the predecessor activity has already started. But exactly when can the successor activity start after the predecessor activity has already been started? Well, both the predecessor and the successor have a start and a finish, and there are at maximum four possible combinations between the start and finish points of the predecessor and the successor activities. Accordingly, there are four kinds of dependencies, also called precedence relationships or logical relationships, listed here: ◆ Finish to start. The initiation of the successor activity depends upon the completion of the predecessor activity—that is, the successor activity cannot be started until the predecessor activity has already been completed. ◆ Finish to finish. The completion of the successor activity depends upon the completion of the predecessor activity—that is, the successor activity cannot be completed until the predecessor activity has already been completed. ◆ Start to start. The initiation of the successor activity depends upon the initiation of the predecessor activity—that is, the successor activity cannot be initiated until the predecessor activity has already been initiated. ◆ Start to finish. The completion of the successor activity depends upon the initiation of the predecessor activity—that is, the successor activity cannot be completed until the predecessor activity has already been initiated. These types of dependencies describe the logical relationships between activities. Where do these relationships come from? To answer this question, the dependencies can be grouped into three categories: ◆ Mandatory dependencies. These are the dependencies inherent to the schedule activities. For example, a software program must be developed before it can be tested. Mandatory dependencies are also referred to as hard logic. ◆ Discretionary dependencies. These are the dependencies at the discretion of the project team. For example, it was possible to perform Activities A and B simultaneously or to perform A after B was finished, but the team decided, for whatever reason, to Sequencing Activities 139 perform B after A was finished. Some of the guidelines for establishing discretionary dependencies can come from the knowledge of best practices within the given application area and from the previous experience of performing a similar project. For example, assume you believe in the 80/20 rule: 80% of activities take 20% of the time and effort. You schedule those 80% of activities before the 20% of activities just to boost the morale of the team. Discretionary dependencies are also referred to as soft logic, preferential logic, or preferred logic. ◆ External dependencies. An external dependency involves a relationship between a project activity and a non-project activity—that is, an activity outside the project. For example, in a movie production project, think of a project activity that involves shooting scenes with lots of tourists skiing. This scene is planned to be shot at a ski resort during the skiing season. This is an example of an external dependency. The dependency between two schedule activities is an example of the logical relationships defined earlier in this chapter. Logical relationships can be displayed in schematic diagrams, called project schedule network diagrams, or just network diagrams for brevity. A common method to develop network diagrams is called the precedence diagramming method (PDM). Precedence diagramming method (PDM). The precedence diagramming method (PDM) is the method to construct a project schedule network diagram in which a box (for example, a rectangle) is used to represent an activity, and an arrow is used to represent dependency between two activities. Because the box containing an activity is called a node, the PDM method is also called activity on the node (AON). The boxes representing activities are called nodes. Figure 4.5 presents an example of a network diagram constructed by using PDM, in which Activity A is a predecessor of Activity B, Activity C is a predecessor of Activities D and G, and so on. FIGURE 4.5 An example of a project schedule network diagram constructed by using the precedence diagramming method (PDM). 140 Chapter 4 PROJECT TIME MANAGEMENT In this diagram, only C and I have more than one successor. In general, PDM supports all four kinds of precedence relationships discussed earlier, but the most commonly used dependency relationship in PDM is finish to start. The start-to-finish relationship is rarely used. Applying leads and lags. In the real world, some activities may need or lend themselves to what are called leads and lags to accurately or effectively define the logical relationships. For example, the finish-to-start dependency means that the successor activity starts where the predecessor activity finishes. Applying a lead means you allow the successor activity to start before the predecessor activity finishes, and applying a lag means you start the successor activity a few units of time after the predecessor activity finishes. Sometimes you might need to make such adjustments in the schedule for effectiveness and efficiency. Schedule network templates. You can use the standardized network diagram templates to save time and to expedite the process of activity sequencing. You can also use the network diagrams from previous projects and modify them for the project at hand. STUDY CHECKPOINT 4.1 A. What is the most common logical relationship used in schedule network diagrams? B. What is the least common logical relationship used in schedule network diagrams? You use these methods to construct project schedule network diagrams, which are the major output of the activity sequencing process. Output of Sequencing Activities The goal of the activity sequencing process is to determine dependencies among the schedule activities and sequence the activities accordingly. The sequencing is presented in network diagrams. Following are the output items from the activity sequencing process: ◆ Project schedule network diagrams. These diagrams, discussed in the previous section, can be created manually or by using an appropriate project management software application. Depending upon a project’s size, you might have multiple network diagrams for it. ◆ Updates to project documents. During the process of sequencing activities, you may identify new necessary activities, split an activity into two, modify activity attributes, add new attributes, or identify a risk related to an activity. Accordingly, you may need to modify some project documents, such as the activity list, activity attributes, and risk register. You can make the activity list, and you can sequence the activities. These are important steps that must be executed. However, to perform the activities, you need resources. The resource requirements for activities need to be figured out. Estimating Activity Resource Requirements 141 Estimating Activity Resource Requirements The resource requirements for an activity are estimated by using the Estimate Activity Resources process. The main purpose of this process is to accomplish the following goals: ◆ Estimate the types of resources needed for a given activity ◆ Estimate the quantities of each type of resource needed for the activity Figure 4.6 shows the Estimate Activity Resources process with its input, tools and techniques, and output. FIGURE 4.6 The Estimate Activity Resources process: input, tools and techniques, and output. The activity list and attributes determined by the Define Activities process are the major input items to activity resource estimating. Input to Activity Resource Estimating The activity list and attributes are the obvious and major inputs to the activity resource estimating process. These and other input items are discussed in the following list. ◆ Activity list and activity attributes. The activity list originally developed during the activity definition process identifies the schedule activities that need the resources. The activity attributes provide the details for the activities, which will be helpful in estimating the resources. ◆ Resource calendars. Resource estimating will require information on the available quantity of resources of different types, such as human, equipment, and material. This information is usually available in the resource calendars, which may also have detailed information about human resources, such as skill level, experience, and geographical location from where the resource will come. Typically, the resource calendar contains the following useful information about the resources: 142 Chapter 4 PROJECT TIME MANAGEMENT ◆ Days and times of day when a resource is available ◆ The passive time for the resource—for example, holidays for human resources ◆ The quantity of each type of available resource ◆ The capability of each resource ◆ Enterprise environmental factors. Information about the infrastructure of the performing organization, such as existing facilities, will be used in identifying the resources and their availability. ◆ Organizational process assets. The organizational process assets useful for activity resource estimating include organizational policies for staffing and purchase of supplies, historical information on what types of resources were used for similar activities in a previous project, and the like. Once you understand the activities, you can use some tools and techniques to determine the resources required to perform those activities. Tools and Techniques for Activity Resource Estimating Following are the tools and techniques used to determine the resources required to perform schedule activities. ◆ Alternatives analysis. Alternative analysis is all about exploring alternative solutions to a problem. In the case of estimating resource requirements, you will need to consider alternatives available for resources needed for some schedule activities. For example, you might need to decide whether you want to buy or develop a tool needed to perform an activity, what types of machines (for example, Windows or Linux) to use, which computers to use to do the development, or what level of skills is needed. ◆ Bottom-up estimating. You might discover that it is rather complex to estimate resources for a given schedule activity. If the problem is inherent to the activity, it might be helpful in certain cases to decompose the activity into smaller components for the purpose of resource estimating, then estimate the resource for each component, and then aggregate the resources to get an estimate for the whole activity. In aggregation, you must consider the possible relationships (overlaps and such) among different components of the activity so you don’t double-count the resources. ◆ Expert judgment. Expert judgment can be used to assess the input and determine the output of the resource estimating process. ◆ Published estimating data. Information published by various vendors, such as costs for resources, production rates, and resource estimates for standard activities, can be useful in estimating resources. ◆ Project management software. Depending upon the sophistication of the resource requirements and the capabilities of the available features, project management software might be useful in estimating and managing the resources. It can also be used to create resource breakdown structures. Estimating Activity Duration 143 You can use a combination of these tools and techniques to generate the output of the resource estimating process. Output of Activity Resource Estimating The resource requirements are the major output of the resource estimating process. These and other output items are discussed in the following list. Activity resource requirements. The main purpose of the activity resource estimating process is to determine the resource requirements for each activity, and therefore this is the major output item from this process. You identify the types of resources required to perform each activity and estimate the required quantity of each identified resource. If a work package in the WBS has multiple activities, the resource estimates for those activities can be aggregated to estimate the resource requirements for the work package. The requirements documents may also include information such as the basis for each estimate, the assumptions made for the estimate, and the availability of the resources. Resource breakdown structure. The resource breakdown structure (RBS) is a hierarchical structure of resource categories and types required to complete the schedule activities of a project. The RBS can be used to identify and analyze the project human resource assignments. Updates to project documents. The identified types of required resources for an activity and the estimated quantity for each identified resource become activity attributes and must be added to the attributes documents. The activity resource estimating might generate modifications to the activity list—for example, to add or delete an activity. It may also cause changes in the resource calendar. Once the activities have been identified and resources required to perform each activity have been estimated, you have enough information to begin estimating the time needed to complete each activity, which is called the activity duration. Estimating Activity Duration Activity duration is the time between start and finish of a schedule activity. Activity duration is estimated in work periods by using the Estimate Activity Durations process. A work period is a measurement of time when the work is in progress; it is measured in hours, days, or months, depending upon the size of the activity. This estimate can be converted to calendar units of time by factoring in the resource’s passive time, such as holidays. For an example, suppose you have estimated that it will take one programmer four days (with eight work hours in a day) to write a program. You also know that the work will start on a Friday, and there will be no work on Saturday and Sunday. Therefore, the activity duration estimate is four days (or 32 hours) measured in work periods and six days measured in calendar units. Figure 4.7 shows the input, tools and techniques, and output for activity duration estimating. 144 Chapter 4 PROJECT TIME MANAGEMENT FIGURE 4.7 The Estimate Activity Durations process: input, tools and techniques, and output. Input to Activity Duration Estimating To estimate the activity duration, you will need information about the activity, the resource requirements for the activity, and the resources available for the activity. This underlines the major input items to the activity duration estimating process. These and other input items are discussed here. Activity list and activity attributes. Because you want to estimate the duration of the activities, the activity list along with the activity attributes, originally developed in the Define Activities process, are the obvious input items to the activity duration estimating process. Activity resource requirements. The work periods required to complete an activity depend on the resources assigned to the activity. For example, suppose it will take four workdays to complete an activity that involves having two programmers write two programs. If only one programmer is available, it will take roughly eight workdays to finish this activity. However, while assigning additional resources to an activity, always consider the following: ◆ Sometimes assigning additional resources might reduce the overall efficiency and productivity. For example, think of two engineers with different skill levels assigned to work on the interrelated components of an activity. ◆ Most of the activities have a threshold beyond which assigning additional resources does not help. For example, installing an operating system on a machine will take the same amount of time regardless of how many system administrators have been assigned to this activity. Resource calendar. The resource calendar, finalized (or modified) during activity resource estimating, contains the type, quantity, availability, and capability of each resource, including the skills of a human resource, which must be considered during activity duration estimating. For example, an experienced programmer can finish the same program in less time than a beginner can. Capability and quantity of available resources, both human and material, can affect the activity duration estimate. For example, if an activity will take four workdays for an engineer to finish, and the engineer can work only four hours a day on this activity, it will take eight calendar days to finish. Estimating Activity Duration 145 Project scope statement. Some assumptions and constraints in the project scope statement can affect activity duration estimates and therefore must be considered. For example, there might be an assumption that part of the work related to an activity has already been performed in a previous project and can be used in this project. If the assumption is true, the activity duration will be less than otherwise. An example of a constraint might be that a specific work package must be finished before a predetermined deadline. This will put a maximum limit on the duration for the activities corresponding to this work package. Enterprise environmental factors. Examples of enterprise environmental factors are some databases that contain the reference data relevant to the activity duration—for instance, how long it takes for a specific government agency to respond to a request. Published commercial information and metrics to measure productivity can also be helpful in duration estimates. Organizational process assets. Organizational process assets that will be useful in estimating activity duration include information from previous projects and a calendar of working days and non-working days. In a nutshell, the activity list and activity resource requirements are the major inputs to the activity duration process. The activity duration estimate is a non-trivial task, and there are various tools and techniques available to perform this task effectively and reliably. Tools and Techniques for Activity Duration Estimating The project schedule depends upon the activity duration estimates. The duration estimates of activities on the critical path will determine the finish date of a project for a given start date. However, there might be many uncertainties involved in the estimate. For example, two programmers, due to the differences in their experience, will take different amounts of time to write the same program. The good news is that there are a number of tools and techniques that you can use in activity duration estimating. Analogous estimating. Analogous estimating techniques estimate the duration of a project or an activity based on the duration of a similar project or an activity in a previous project. Therefore, historical information and expert judgment goes into this estimating technique. The accuracy of the estimate depends upon how similar the activities are and whether the team member who will perform the activity has the same level of expertise and experience as the team member from the previous project. This technique is useful when there is not enough detail information about the project or a project activity available—for example, in the early stages of a project. This estimating technique is less expensive but also less accurate. It’s a useful technique for estimating the overall duration of the project even when the details at the level of activities are not available. Parametric estimating. This is a quantitative technique used to calculate the activity duration when the productivity rate of the resource performing the activity is available. You use a formula such as the following one to calculate the duration: Activity duration = Units of work in the activity / Productivity rate of the resources 146 Chapter 4 PROJECT TIME MANAGEMENT For example, if you know that a team assigned to the activity of burying 40 miles of cable can bury two miles of cable in one day, the duration calculation can be performed as follows: Activity duration = 40 miles / (2 miles/day) = 20 days Three-point estimating. This method addresses the issue of uncertainty in estimating the activity duration. The uncertainty in the duration estimate can be calculated by making a threepoint estimate in which each point corresponds to one of the following estimate types: ◆ Most likely scenario. The activity duration is calculated in the most practical terms by factoring in resources likely to be assigned, realistic expectations of the resources, dependencies, and interruptions. ◆ Optimistic scenario. This is the best-case version of the situation described in the most likely scenario. ◆ Pessimistic scenario. This is the worst-case version of the situation described in the most likely scenario. The spread of these three estimates determines the uncertainty. The resultant duration is calculated by taking the average of the three estimates. For example, if the duration for an activity is estimated to be 30 days for the most likely scenario, 27 days for the optimistic scenario, and 33 days for the pessimistic scenario, then the average duration is 30 days and the uncertainty is ± 3 days, which can be expressed as: Duration = 30 ± 3 days It’s equivalent to saying that the activity duration is 30 days, give or take three days. However, the most likely scenario may be given more weight than the other two scenarios. Therefore, the expected duration can be calculated by using a formula where te is the expected duration, tm is the duration in the most likely scenario, to is the duration in the optimistic scenario, tp is the duration in the pessimistic scenario and wm., wo, and wp are the weights given to the most likely, optimistic, and pessimistic scenarios respectively. The PERT approach illustrated in Study Checkpoint 4.2 is a specific case of this general approach. STUDY CHECKPOINT 4.2 In the program evaluation and review technique (PERT), the most likely scenario is given a weight of 4 as compared to the weight of 1 for each of the pessimistic and optimistic scenarios. The pessimistic estimate for an activity is 20 days, the optimistic estimate is 10 days, and the most likely estimate is 15 days. Calculate the expected estimate by using the PERT technique. Estimating Activity Duration 147 Reserve analysis. Reserve analysis is used to incorporate a time cushion into your schedule; this cushion is called a contingency reserve, a time reserve, or a time buffer. The whole idea is to accommodate the possibility of schedule risks. One method of calculating the contingency reserve is to take a percentage of the original activity duration estimate as the contingency reserve. It can also be estimated by using quantitative analysis methods. Later, when more information about the project becomes available, the contingency reserve can be reduced or eliminated. Expert judgment. Expert judgment can be used to estimate the whole duration of an activity when not enough information is available. It can also be used to estimate some parameters to be used in other methods—for example, what percentage of the original activity duration estimate should be used as a contingency reserve—and in comparing an activity to a similar activity in a previous project during analogous estimating. Note that, in general, a combination of techniques is used to estimate the duration of an activity. For example, you can use the analogous technique and expert judgment to estimate the productivity rate of resources and then use that productivity rate in parametric analysis to calculate the activity duration. Analogous estimating itself uses historical information and expert judgment. Output of Activity Duration Estimating Guess what the output of the activity duration estimating process is. Yes, you are right: It is the activity duration estimates! Regardless of which technique you use, these estimates are quantitative assessments of the required time units to finish activities, such as five days or 10 weeks. As shown earlier, you can also assign an uncertainty to the estimate, such as 20 ± 2 days to say that the activity will take at least 18 days and at most 22 days. The duration of an activity is an attribute of the activity. Therefore, you update the activity attributes, originally developed in the Define Activities process, to include the activity durations. In a nutshell, there are two output items of the activity duration estimating process: ◆ Activity duration estimates ◆ Updates to activity attributes and assumptions about skill level and availability of resources By using various processes discussed in this chapter, you have identified schedule activities, arranged them in proper sequence, determined resource requirements for them, and estimated their durations. All these tasks and accomplishments are a means to an end called project schedule development. 148 Chapter 4 PROJECT TIME MANAGEMENT Developing the Project Schedule The project work is composed of individual activities. So, the processes previously discussed in this chapter deal with the activities: defining activities, estimating activity durations, and estimating resource requirements of the activities. By using these processes, you work out a few schedule-related pieces at the activity level, which come together as the project schedule when you crank them through the schedule development process, formally called Develop Schedule. Until you have a realistic project schedule, you do not have a project. A project schedule has schedule activities sandwiched between the project start date and the project finish date. Figure 4.8 shows the Develop Schedule process used to develop the project schedule. FIGURE 4.8 The Develop Schedule process: input, tools and techniques, and output. All the processes discussed in this chapter so far had a common goal: schedule development. Therefore, the major output items of all the processes discussed in this chapter are the inputs to the schedule development process. Input to Schedule Development The following output items from the schedule-related processes discussed in this chapter directly support the schedule development process: ◆ Activity list and activity attributes ◆ Project schedule network diagrams showing the dependencies among activities ◆ Activity resource requirements and resource calendars ◆ Activity duration estimates The project scope statement and other input items can be useful in ways described in the following list. Project scope statement. The assumptions and constraints in the project scope statement can affect the project schedule and therefore must be considered in developing the schedule. The following two types of time-related constraints should get special attention. Developing the Project Schedule 149 ◆ Hard deadlines on start and finish dates. Some activities or work packages might have constraints on their start or finish dates. For example, there might be a situation in which an activity cannot be started before a certain date, must be finished before a certain date, or both. Where do these date constraints come from? They can come from various sources, such as a date in the contract, a date determined by the market window, delivery of material from an external vendor, and the like. ◆ Time constraints on deliverables. These constraints can come from the customer, the sponsor, or any other stakeholder in terms of deadlines for certain major deliverables or milestones. Other projects inside or outside your organization might be depending on these constraints. So, once scheduled, these deadlines are constraints and can only be changed through the approval process. Environmental factors and process assets. Scheduling tools are an example of enterprise environmental factors, and scheduling methodology and project calendars are examples of organizational process assets that can be useful in developing the schedule. To summarize, the output of various time management processes is used as input to the schedule development process, which uses a variety of tools and techniques to iron out the project schedule. Tools and Techniques for Schedule Development Once you have the network diagrams for the activities, as well as the activity duration estimates, you are well equipped to start scheduling the project. The remaining main concerns include the following: ◆ The actual start date ◆ Uncertainty on the availability of resources ◆ Identification of and preparation for activities on the critical path ◆ Risks involved, or what-if scenarios ◆ The hard start/finish dates for activities or for the project that came down the pipeline from very important stakeholders Various tools and techniques discussed in the following sections can be used to address these concerns while you are hammering out the project schedule. Schedule Network Analysis A schedule network analysis is a technique used to generate a project schedule by identifying the early and late start and finish dates for the project. The analysis accomplishes this task by using various analytical techniques, such as critical path method, critical chain method, whatif analysis, and resource leveling. These techniques are discussed in the following list. Critical path method. This is the schedule network analysis technique used to identify the schedule flexibility and the critical path of the project schedule network diagram. The critical path is the longest path (sequence of activities) in a project schedule network diagram. Because 150 Chapter 4 PROJECT TIME MANAGEMENT it is the longest path, it determines the duration of the project, and hence the finish date of the project given the start date. An example will explain this. Consider the network diagram presented in Figure 4.9. The boxes in the figure represent activities, such as Activity A followed by Activity B, and the number on top of a box represents the duration of the activity in time units, such as days. FIGURE 4.9 An example of a project schedule network diagram. The duration of an activity is represented by the number shown on top of the box that represents the activity. Table 4.2 shows the calculations for the duration of each path of the network diagram by adding the durations of the individual activities on the path. You can see from Table 4.2 that the path Start-F-G-H-Finish is the critical path because it is the longest path in the diagram, at 21 days. This means if the project start date is January 2, the project finish date will be January 23 (2+21), given that the duration is shown in calendar time units. Table 4.2 Path Durations Calculated from the Network Diagram Shown in Figure 4.9 Path Durations of Activities Path Duration Start-A-B-Finish 5+3 8 Start-C-D-E-Finish 5+4+5 14 Start-C-G-H-Finish 5+6+8 19 Start-F-G-H-Finish 7+6+8 21 Start-I-G-H-Finish 5+6+8 19 Start-I-J-H-Finish 5+4+8 17 Developing the Project Schedule 151 The second important feature of the critical path method is to identify the flexibility in the project schedule by calculating the early and late start and finish dates of each activity on each path. The schedule flexibility of an activity is measured by the positive difference between the late start date and the early start date for the activity, and it is called float time or total float. Table 4.3 shows calculations for the early and late start and finish dates and the float time for each activity in the network diagram being analyzed. The early start and finish dates of activities on a path are calculated by using the forward-pass method, which means you start your calculations from the start point (left-most) and make your way forward. As an example, consider the path Start-A-B-Finish in the network diagram shown in Figure 4.9. Because A is the first activity on the path, its early start is Day 0. Because B depends on the completion of A, and A takes five days to finish, the early start date for B is the early start date of A plus the duration of A—that is, 0+5=5. The late start and finish dates are calculated using the backward-pass method, which means you start your calculations from the finish point. The project finish date determined by the critical path is Day 21, given that the project start date is Day 0. Because Activity B has a duration of three days, it must be started no later than Day 18 (21–3=18). Therefore, Day 18 is the late start date of Activity B. Activity A has a duration of five days, so given that B must start on Day 18, A must not start later than Day 13 (18–5=13). Therefore, the late start date for A is Day 13. The float times are calculated as follows: Float time for A = late start – early start = 13 – 0 = 13 Float time for B = late start – early start = 18 – 5 = 13 Table 4.3 Early and Late Start and Finish Dates for Activities in the Network Diagram Shown in Figure 4.9 Activity Early Start Early Finish A 0 5 13 18 13 B 5 8 18 21 13 C 0 5 2 (not 7) 12 2 D 5 9 12 16 7 E 9 14 16 21 7 F 0 7 0 7 0 G 7 13 7 13 0 H 13 21 13 21 0 I 0 5 2 (not 4) 9 2 J 5 9 9 13 4 Late Start Late Finish Float Time 152 Chapter 4 PROJECT TIME MANAGEMENT Note that each of the activities on the critical path (F, G, and H) has a float time of zero. This obviously is a source of schedule risk. Here is the summary of terms related to the float time: ◆ Float. Freedom to adjust; also called slack. ◆ Free float. The amount of time by which a given schedule activity can be delayed without delaying the early start date of any immediately following schedule activity. ◆ Total float. The total amount of time by which a schedule activity can be delayed from its early start date without delaying the project finish date or any other schedule constraint, such as a milestone. Total float can be positive, zero, or negative. NOTE The critical path is usually characterized by zero total float time but may even have a negative float time and hence poses a schedule risk. A negative float time means that you will need to do some activities on the critical path in parallel in order to meet the deadline. Therefore, you must monitor the activities on all critical paths very closely during the execution of the project. In a nutshell, CPM theoretically calculates the early start and finish dates and late start and finish dates by performing forward-pass and backward-pass analysis on the schedule network diagram. CPM assumes that the resource requirements will be met. However, practically speaking, resources are always limited, and there are uncertainties in the activity durations and resource estimates. This is where the critical chain method comes into the picture. Critical chain method. The critical chain method is the schedule network analysis technique used to modify or adjust the project schedule to account for limited resources. This technique takes into account the uncertainties of the activity durations due to the uncertainty of the availability of resources. It uses the schedule network diagrams to identify the critical paths and the schedule flexibility, just like the critical path method. The only difference is that in this technique, you work from more than one network diagram. For example, the durations in the first network are based on the planned scenario regarding the availability of resources. You can draw another network diagram based on the pessimistic scenario regarding the availability of resources. The durations of some activities in the second diagram will be longer than the first diagram, and the second diagram might even have a different or an additional critical path. The extra durations in the second diagram are called duration buffers. So, the focus of the critical chain method is on managing the duration buffers and the uncertainties in the availability of resources applied to the planned schedule activities. Resource leveling. Resource leveling is not an independent schedule network analysis method. It is applied to the schedule that has already been analyzed using other methods, such as the critical path method or the critical chain method. The resource leveling technique is applied to address the resource needs of activities that must be performed to meet specific delivery dates. Resource leveling involves taking a part of the resources from one activity and assigning it to another. This will change the activity durations and can also result in a change of critical paths. Developing the Project Schedule 153 What-if scenario analysis. The purpose of what-if scenario analysis is to calculate the effects of a specific scenario on the schedule—for example, how the schedule will be affected if a vendor does not make the delivery of a major component on the promised date. Because a what-if scenario by definition represents uncertainty, this analysis often leads to risk planning, which might include changing the schedule or changing the network diagram to get a few activities out of harm’s way if possible. As you have seen, the critical path method is used to develop a schedule for given resources, whereas the critical chain method factors in the uncertainty of the availability of the resources. The resource leveling technique is used to move the resources around to meet the resource needs of the activities that must be accomplished on a specific date. In other words, in an ideal world in which the required (or planned) resources are guaranteed, you do not need the critical chain method and resource leveling; just the critical path method will do. Let’s assume you have used the critical path method to determine the schedule for a project. You have also applied other techniques, such as the critical chain method and resource leveling. The final realistic schedule that you have come up with has an unacceptable project duration (the length of the critical path). What do you do? This is where the schedule compression technique comprised of several methods or sub-techniques comes to your rescue. Schedule Compression Schedule compression is an attempt to shorten the project schedule without changing the project scope. It may be necessary in order to deal with schedule-related constraints and objectives. It is true that you, the project manager, build the schedule through cold, hard mathematical analysis, and you don’t just accept whatever schedule goals come down the pipeline from elsewhere, such as from the customer or the project sponsor. However, once you have the schedule built through analysis, you can attempt to accommodate some critical stakeholder expectations or hard deadlines, such as a predetermined project finish date. I have already discussed one such method, called resource leveling, to accommodate hard deadlines for activities. In this section, I will discuss two more methods for schedule compression: crashing and fast tracking. Fast tracking. This is a project schedule compression technique used to decrease the project duration by performing project phases or some schedule activities within a phase in parallel that would normally be performed in sequence. For example, testing of a product can start when some of its components are finished, rather than waiting for the whole product to be completed. Therefore, in fast tracking, you utilize leads, lags, and float time. Crashing. This is a project schedule compression technique in which cost and schedule tradeoffs are analyzed to decrease the project duration with minimal additional cost. A number of alternatives are analyzed, including the assignment of additional resources. Approving overtime is another example of crashing. Crashing only works for schedule activities whose duration can be shortened by allocating additional resources. Crashing may increase the cost and the risk. 154 Chapter 4 PROJECT TIME MANAGEMENT TIP Crashing usually involves assigning more resources and hence increasing the cost. However, guard yourself against the misconception that additional resources will linearly improve the performance. For example, if one programmer can develop a program in eight days, it does not necessarily mean that two programmers will develop the same program in four days, because there will be overhead, such as the initial less-productive stage of the newly assigned resource, the time taken to reallocate the work, the interaction among the resources, and so on. Other Tools and Techniques In addition to the main techniques to develop the project schedule, which I already discussed, there are some other tools and techniques for developing the project schedule that I will discuss in this list. Applying leads and lags. Just like in the activity sequencing process, leads and lags can be applied during the development of the project schedule. If you applied some leads and lags during the activity sequencing process, it is time to consider whether you need to adjust those. This adjustment might be necessary to create a realistic schedule. Project management software. After you have the data for the schedule development created by the processes discussed in this chapter, it is a common practice to use project management software to build the actual schedule. Because they are automated, the scheduling tools expedite the scheduling process and reduce the probability of errors in the schedule. In a nutshell, the main techniques to develop a project schedule include network diagram analysis (critical path method and critical chain method), schedule compression (fast tracking and crashing), and resource leveling. You use these techniques to generate the output of the schedule development process. Output of the Schedule Development Process The planned project schedule is an obvious output of the schedule development process. This and other output items are discussed in this list. Project schedule. The project schedule includes a planned start date and a planned finish date for each schedule activity. The schedule will be considered preliminary until the resources have been assigned to perform the activities according to the schedule. Although a schedule for a simple project might be presented in a tabular form, typically a project schedule is presented in one of the following graphical formats: Developing the Project Schedule 155 ◆ Project schedule network diagram. These diagrams present the schedule activities on a timescale with a start and finish date for each activity and hence show the dependencies of activities on each other. Because they show the dependencies—that is, the logic—they are also called logic charts. ◆ Bar chart. In these charts the activities are represented by bars, with each bar showing the start date, the finish date, and the duration of the activity. They are easy to read and are often used in presentations. ◆ Milestone chart. These are typically bar charts representing only the milestones, not all the schedule activities. Schedule data. This is the supporting data for the project schedule and consists of the following: ◆ The essential data consists of schedule activities, schedule milestones, activity attributes, and documentation of all identified assumptions and constraints. ◆ Resource requirements by time periods. ◆ Alternative schedules—for example, schedules based on best-case and worst-case scenarios. ◆ Schedule contingency reserves. TIP The schedule data may be enriched with items such as delivery schedules, order schedules, and resource histograms depending on the nature of the project. This data is used to create the version of the schedule that is approved by the project management team and becomes the schedule baseline. Schedule baseline. This is a specific version of the project schedule that is accepted and approved by the project management team as a baseline against which the progress of the project will be measured. This version of the schedule is developed from the schedule network analysis described earlier. Updates to project documents. During the process of developing the schedule, updates to the following documents may happen: ◆ Resource requirements. The schedule development process might change the initial estimate for the types and quantities of required resources. ◆ Activity attributes. Resource requirements or any other activity attributes that have changed must be updated. ◆ Project calendar. Any update to the project calendar must be documented. For example, each project may use different calendar units in the project schedule. 156 Chapter 4 PROJECT TIME MANAGEMENT NOTE Project schedule development is an iterative process. For example, it might be necessary to review and revise the duration and resource estimates for some activities to create a project schedule that will be approved. The approved project schedule will act as a baseline against which project progress will be tracked. As mentioned earlier, the approved project schedule is used as a baseline to track the project progress. To some extent, the schedule development (or modification) continues throughout project execution due to the approved changes and the risk occurrences. STUDY CHECKPOINT 4.3 Lora Nirvana is the project manager for the Sequence the DNA of a Buffalo (SDB) project. Match each item in the first column of the following table to the correct item in the second column. Output of the Develop Schedule Process A. Schedule data B. Project document updates C. Schedule D. Schedule baseline Description 1. A bar chart that includes all the activities of the project and also includes milestones. Lora points out this bar chart to the project sponsor to show where they are in the execution of the project. 2. A bar chart hanging on the calendar that has never changed once it was approved. Lora compares the current bar chart to this bar chart to show the progress. 3. On a bar chart, Lora points to the dates when she will have the DNA sample isolated and purified, when she will get the DNA sample run through the genetic analyzer, when she will receive the results from the analyzer, and when the results will be published on the Internet. 4. After realizing that their chosen vendor has a track record of sending the DNA analysis kits late, Lora writes something into the risk register. Once the schedule is developed and approved, it needs to be controlled throughout the lifecycle of the project. Controlling Schedule 157 Controlling Schedule Schedule control has a two-pronged goal—to ensure that the project is progressing on time as planned and to monitor any changes to this progress. As a project manager, you should be out in front of the project, performing the following tasks on a regular basis: ◆ Determine the current status of the project schedule. ◆ Influence the factors that generate schedule changes. ◆ Determine whether the project schedule has changed—for example, if some activities are running late. ◆ Manage the changes as they occur. You detect a schedule change by comparing the execution time to the time in the schedule baseline, which is a major input item into the schedule control process, as shown in Figure 4.10. FIGURE 4.10 The Control Schedule process: input, tools and techniques, and output. Input to Schedule Control To control the project schedule, you need to know what the schedule baseline (that is, the expectation) is, how the project is performing from the perspective of schedule, and what the plans are to monitor the schedule. Accordingly, the input items to the schedule control process are the following: ◆ The schedule management plan. This plan specifies how to monitor and control the project at hand. ◆ Schedule baseline. This is the approved version of the schedule, against which the schedule performance of the project will be measured. ◆ Performance reports. These reports provide information on the schedule performance of the project, such as missed and met planned dates. 158 Chapter 4 PROJECT TIME MANAGEMENT ◆ Approved change requests. These are requests to change the schedule or other change requests that will affect the schedule. Approved change requests can update the schedule baseline. Tools and Techniques for Schedule Control The schedule is monitored by progress reporting and performance measurements and is controlled using the schedule control system. These and other tools and techniques are discussed in this section. Performance reviews and progress reporting. Progress reports and current schedule status are key items to monitor and control the schedule. They can include the finished activities, the percentage of in-progress activities that have been completed, and remaining durations for unfinished activities. This reporting comes from performance reviews, which use earned value management (EVM) and schedule performance index (SPI), explained in Chapter 5. Performance measurement and analysis. The following tools and techniques can be used to measure and analyze the schedule performance of the project: ◆ Performance measurement techniques. These techniques are used to calculate the schedule variance and schedule performance index and are discussed in the “Measuring Performance” section in Chapter 5, “Project Cost Management.” The schedule variance discussed there is in terms of cost, but you can also perform a barebones schedule variance analysis based on the start and end dates of the schedule activities. ◆ Variance analysis. Performing a barebones schedule variance analysis is crucial to schedule monitoring because it reveals the deviation of the actual start and finish dates from the planned start and finish dates of schedule activities. It might suggest corrective actions to be taken to keep the project on track. Bar charts can be used to facilitate the schedule variance analysis. You can draw two bars corresponding to one schedule activity—one bar shows the actual progress, and the other bar shows the expected progress according to the baseline. This is a great tool to visually display where the schedule has progressed as planned and where it has slipped. TIP A schedule variance does not necessarily mean that a schedule change is required. For example, a delay on a schedule activity that is not on the critical path might not trigger any schedule change. Project management software. You can use project management software for scheduling to track planned start/finish dates versus actual dates for schedule activities. This software also enables you to predict the effects of project schedule changes. These are important pieces of information for monitoring and controlling the schedule. Project management software may include Controlling Schedule 159 the schedule change control system that you use to receive, evaluate, and process schedule changes. It can include forms, procedures, approval committees, and tracking systems. Another tool that project management software may include is the scheduling tool. Other tools and techniques. Other tools and techniques that can be used to monitor and control the project schedule include schedule compression techniques, adjusting leads and lags, what-if scenario analysis, and resource leveling techniques. These techniques have already been discussed in this chapter. Output of Schedule Control Schedule performance measurements and recommendations for actions based on the measurements and progress reports are the important output items of the schedule control process. Performance measurements. The results from schedule performance measurements, such as the schedule variance (SV) and schedule performance index (SPI), should be documented and communicated to the stakeholders. These measurements might trigger recommendations for corrective actions and change requests. TIP Remember that corrective actions are not about going back and fixing past mistakes. Rather, they’re about ensuring that future results match with the plan. You can do this by influencing the future results, such as expediting the execution, or by changing the plan. Updates. The following updates can result from the schedule control process: ◆ Schedule updates. Schedule changes can happen at the activity level (the start/end date of an activity has changed) or at the project level (the start/end date of the project has changed). A schedule change at the project level is called a schedule revision. For example, when the schedule scope is expanded, the project end date might have to be changed to allow the extra work. All significant schedule changes must be reported to the stakeholders. ◆ Activity updates. The schedule changes and the project progress will cause changes in the activity list and in the list of activity attributes. These changes must be documented. ◆ Project management plan. The schedule management plan, a component of the project management plan, is updated to reflect the changes that occur during the schedule control process. 160 Chapter 4 PROJECT TIME MANAGEMENT ◆ Organizational process assets. The lessons learned from the schedule control process can be documented to the historical database. Following are some examples: ◆ The causes of schedule variance ◆ The reasons for choosing the corrective actions that were taken ◆ The effectiveness of the corrective actions Future projects can make use of this information. Change requests and recommendations. The schedule performance analysis and progress report review can result in requests for changes to the project schedule baseline. These changes must be processed through the integrated change control process for approval. As with any other change, you must think through whether a change to the schedule baseline has any other effect across the project. If it does, you might need to update the corresponding component of the project management plan accordingly. Change requests may include recommended corrective actions. The goal of schedule-related corrective actions is to bring the future schedule performance in line with the schedule baseline—that is, the approved version of the planned schedule. To that end, the following actions can be taken: ◆ Expedite the execution to ensure that schedule activities are completed on time or with minimal delay. ◆ Perform a root cause analysis to identify the causes of the schedule variance. ◆ Make plans to recover from the schedule delay. The three most important takeaways from this chapter are as follows: ◆ Various time-management processes are used to produce schedule data—a list of schedule activities and attributes for each activity, such as required resources and the duration of the activity. ◆ The schedule data is used to develop the project schedule, which is an iterative process due to the uncertainties in the schedule data and due to the changes during the project execution. Nevertheless, the approved version of the planned schedule is used as a baseline to track the project progress. ◆ The schedule needs to be controlled to keep the project on track. The major output items of the schedule control process are performance measurements and change requests resulting, for example, from comparing these measurements to the performance baseline. Summary Project schedule development is a journey that begins with decomposing the work packages in the WBS to project activities and ends with an approved schedule for performing those activities. Once developed, the schedule needs to be controlled. The processes used to perform all these activities belong to project time management. The planning part of time management Summary 161 addresses some basic questions: What are the activities that need to be performed to complete the project, what type and quantity of resources are required to perform these activities, and when? The Define Activities process is used to decompose the work packages in the WBS into schedule activities. The resulting activity list is used by the activity sequencing process to generate network diagrams, which display the dependencies among the activities. The commonly used method to construct network diagrams is the precedence diagramming method (PDM). The activity list and attributes are also used to determine the resource requirements for the project. Given the available resource, you can estimate the activity duration—that is, the time it will take to perform the activity. By using various time-management processes discussed in this chapter, you identify schedule activities, arrange them in proper sequence, determine resource requirements for them, and estimate their durations. All these tasks and accomplishments are a means to an end called Develop Schedule. You typically use the critical path method to develop the project schedule from a network diagram. After you have a schedule, you can use schedule compression methods, such as fast tracking and crashing, to accommodate hard deadlines. Schedule development is an iterative process that can continue well into the project execution due to approved changes and risk occurrences. However, the approved planned project schedule is used as a baseline to track the project progress. You need to control the schedule, which includes monitoring the status of the project progress and controlling the changes to the schedule baseline. Due to changes in the project management plan and due to evolving risks, revising and maintaining a realistic schedule continues throughout the project lifecycle. You need resources, such as human resources that will do the project work and funding to get the human resources and other resources. So, a project has a cost attached to it, and cost needs to be managed by using the processes of project cost management. This is the topic of the next chapter. Exam’s Eye View Comprehend ◆ The major task of the Define Activities process is to generate the activity list (output) by decomposing (or arranging) the work packages of the WBS (input) into activities. ◆ The major task of the Sequence Activities process is to determine the dependencies among the activities in the activity list (input) and display those dependencies in the network diagrams (output). ◆ After the activity resource requirements have been determined, the duration for an activity can be estimated for a given resource. ◆ Network diagrams with activity durations assigned to each activity can be used to develop the schedule. The approved project schedule acts as a baseline against which the project progress is tracked. 162 Chapter 4 PROJECT TIME MANAGEMENT Look Out ◆ Activity duration is estimated for a given resource committed to the activity. Changing the quantity of the resource will change the duration estimate. ◆ Activity duration measured in work periods does not include holidays, whereas the duration measured in calendar units does. For example, the activity duration from Friday to the following Tuesday is three days when measured in work units and five days when measured in calendar units, given that no work is done on Saturday and Sunday. ◆ Free float refers to the amount of time by which a given schedule activity can be delayed without delaying the early start date of any immediately following schedule activity, whereas total float refers to the total amount of time by which a schedule activity can be delayed from its early start date without delaying the project finish date or any other schedule constraint, such as a milestone. ◆ The critical path has zero or negative total float time and thus poses a schedule risk. Therefore, you must monitor the activities on all critical paths very closely during the execution of the project. ◆ A negative float time means that a successor activity may need to be started before the predecessor activity is finished. Memorize ◆ The approved project schedule called the schedule baseline becomes part of the project management plan. ◆ In PDM, finish to start is the most commonly used dependency relationship, whereas start to finish is the least used. ◆ Fast tracking compresses the schedule by performing activities simultaneously that would otherwise be performed in sequence, whereas crashing compresses the schedule by assigning more resources. ◆ The schedule control process converts the time (schedule)–related work performance information into work performance measurements. ◆ Total float time can be positive, zero, or negative. Review Questions Review Questions 1. Which of the following is the most commonly used network diagramming method? A. Critical path method (CPM) B. Critical chain method (CCM) C. Precedence diagramming method (PDM) D. Arrow diagramming method (ADM) 2. What is the crashing technique used for? A. Network diagramming B. Duration compression C. Cost reduction D. Activity sequencing 3. Which of the following is a true statement about the critical path? A. Each activity on the critical path has zero float time. B. It controls the project finish date. C. It controls the project start date. D. It is the shortest sequence in the network diagram. 4. In your research project on tourism, you must collect data before the tourist season ends because the project involves interviewing tourists. The data-collection activity has which of the following kinds of dependency? A. Mandatory B. External C. Internal D. Discretionary 5. You know from a network diagram that Activity B cannot start until Activity A is finished. Which of the following are true? A. Activities A and B have a start-to-finish dependency. B. Activities A and B have a finish-to-start dependency. C. Activity B has a mandatory dependency on Activity A. D. Activities A and B are on a critical path. 163 164 Chapter 4 PROJECT TIME MANAGEMENT 6. Why should you monitor the activities on the critical path more closely? A. Because each activity on the critical path has zero float time and thereby poses a schedule risk. B. Because the activities on the critical path need to be performed before the activities on other paths. C. Because the activities on the critical path are critical to the organization’s strategy. D. Because the activities on noncritical paths depend upon the activities on the critical path. 7. You estimate the duration of an activity as five days because an expert told you that it took five days to complete a similar activity in a previous project. Which of the following methods have you used for your activity duration estimate? A. Parametric estimating B. Expert judgment C. Analogous estimating D. Delphi technique 8. You have developed the schedule for your project, and you’ve called the kickoff meet- ing. A team member who is responsible for an activity comes to you and tells you that the activity cannot be performed within the allocated time because some pieces were left out during activity definition. The revised estimate will add two more days to the activity duration, but the activity is not on the critical path. Which of the following actions will you take? A. Go to the team member’s functional manager and find out whether the team member’s estimate is correct. B. Accept the new estimate but do not change the schedule. C. Accept the new estimate and update the schedule accordingly. D. Put the new estimate through the integrated change control process. 9. The amount of time by which an activity can be delayed without changing the project finish date is called: A. Float time B. Lag time C. Grace time D. Activity gradient Review Questions 10. You are the project manager of a project that is running behind schedule. The project sponsor is very unhappy at the new finish date that you proposed, but he has accepted it. However, you also requested extra funds to support the extended time of work, and the sponsor has refused to supply more funds and is threatening to cancel the project if you cannot finish it within the planned budget. What are your options? A. Crashing B. Fast tracking C. Asking the executive management for a new sponsor D. Speaking with the customer directly without involving the sponsor to see whether the customer can increase the budget 11. Consider the following network diagram. Which of the following is the critical path? A. Start-C-D-E-Finish B. Start-I-G-E-Finish C. Start-I-G-H-Finish D. Start-I-J-H-Finish 12. What is the float for Activity G in the network diagram in Question 11? A. 3 B. 2 C. 1 D. 0 13. What is the length of the critical path in the network diagram shown in Question 11? A. 20 B. 21 C. 22 D. 31 E. 9 165 166 Chapter 4 PROJECT TIME MANAGEMENT 14. You use a three-point estimate for activity duration estimating. An activity has a duration of 9 days for an optimistic scenario, 18 days for a pessimistic scenario, and 12 days for the most likely scenario. Which of the following will you take as the duration estimate for this activity if you use the PERT analysis? A. 13 days B. 12.5 days C. 12 days D. 18 days 15. Which of the following is not an input item to the Define Activities process? A. The WBS B. The activity duration C. The project scope statement D. The WBS dictionary 16. Which of the following is not an output of the schedule control process? A. Recommended corrective actions B. Updates to the schedule baseline C. Performance measurements D. Budget review