In this tutorial I explain, Project Time Management that provides a basis to activity definition, Sequencing them in an order, Estimate Resource and Duration, Develop schedule and control it.
In a simplest way to understand the Project, it is a collection of different Activities/Tasks those are needed to be performed in an order to achieve projected results. To execute/perform those tasks certain resources (material or/and labor) are required for a period of time. And those resources should operate in a Controlled way. All of these specifications are achieved by Time Management Knowledge Area of PMBOK Guide. Look at Processes listed in the above table, they exactly satisfy these requirements. Even those names are self explanatory. The Major out come of this Knowledge Area will be Time Management Plan which is part of the big Project Plan document. (Please note the difference between the MS Project Plan and PMI Project Plan. MS Project Plan that we lay down to run the project is just sub-set of the Project Plan suggested PMI. PMI Project Plan is an elaborative document constituting all strategies to run the project) |
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Apart from all other factors involved to make a Successful Project, Tight Schedule is the foundation for well managed project. Schedule can be treated as a tool that identifies and organizes different required project tasks in a sequence and presented in the form of a Plan.
Schedule Management Plan is one of Plans part of the big Project Management Plan is major out come of this Knowledge Area. (“Click here” to see all other documents part of Project Management Plan).
Benefits of Schedule Management: (few them are listed below)
· It can be used as basis for monitoring, controlling and tracking.
· How to use resources effectively and in most efficient way
· Which activities are crucial to finish the project (Critical Path)
To develop a proper schedule we need to breakdown bigger work packages of WBS (Work Breakdown structure) to Activities. Activities are should be at such a granular level where further breakdown is meaning less.
Schedule Management Software: For scheduling purposes we can use Computer based software. I used many Scheduling and Tracking software. But out of all I like Microsoft Project. Now it is available in Server Edition to track Enterprise Projects. I bet this is the best software in the world for this purpose.
Rolling Wave Planning: When we start breaking down the Work packages of WBS into Activities we might know details for few work packages. At that time we might leave those work packages as it is at higher level and plan accordingly. When we really come to execute those work packages then we can further break down in to activity level. Estimating at higher level needs lot of "Expert Judgment" techniques.
Milestone List: Project can't be tracked against single end point. There should be some intermediate control points (significantly distinguishable). Management can check the Project performance against those intermediate Milestones. Examples: Ground level design completion, First pass build completion, .. so on. One should not mistake milestones with Phases. Milestones are intermediate touch points within a Phase.
Activity Definition: Team has to break big chunks of work packets into smaller activities which are manageable in all sense like scheduling, resourcing and tracking. In this process Activity List is on of major outcomes.
after this Activity Sequencing is next process, and following table shows inputs, tools and outputs of that process.
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Triple Constraints: Time, Cost, Scope are initially known as Triple constraints. Which means if you change one of these three there will be direct impact on other 2? As project Management methodology is evolving Quality and Risk were also added to those constraints.
Activity Sequencing: All Activities those defined and listed can't start at one time. (At least resourcing wise it would be impossible). Normally there will dependencies between activities. One activity will occur after other activity. Putting activities on Activity List in a Sequence is major purpose of this process. This can be in tabular format by showing successors and predecessors (MS Project has this feature). More commonly it can be represented in pictorial format. It is similar to "Flow Chart". See following diagram.
Activity Dependencies: There are 4 types of Activity dependencies
- Finish to Start: Preceding activity must finish before successor starts.
- Finish to Finish: Proceeding activity must finish to finish successor activity.
- Start to Start: Preceding Activity must start to Start Successor
- Start to Finish: Preceding Activity must Start before successor can finish. For example, Get an approval to start constructing a house. But in this dependency we start construction and get an approval before finishing the construction. Rarely used dependency.
These dependencies can be categorized as Hard dependencies or Soft Dependencies. Hard Dependencies are mandatory to follow where as Soft Dependencies are good to follow but they are not mandatory.
Drawing Sequencing Diagrams also called Network Diagrams: Many methods are provided but 2 methods are most common and another method is worth mentioning.
- Activity on Node
- Activity on Arrow
Activity on Node (AON) or Precedence Diagram Method (PDM): Nodes represent activities and draw arrows to show the dependencies. The above Sequence diagram is an example of this method.
Activity on Arrow (AOA) or Arrow Diagram Method (ADM): Nodes are transition points (Dependencies) and Arrows represents the activities. Sometime this is so confusing to understand. In those cases those nodes are given names and activities are treated as processes.
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Activity Resource Estimation:
By now you might have completed listing all activities in the projects and sequenced those. Now you have to identify what kind of resources is required to execute those activities those can be People, equipment, or material. The goal of this process is to generate Activity Resource Requirement. We are not yet ready for effort estimation yet. In this process we are identifying only required resources.
Bottom-up Estimating is a tool used here. This technique is used in various processes in different contexts. Here if we are using this to identify what kind of resources are needed at Activity level so that similar kind of activities can be assigned to same resource. So when you ask for cross team resources you can tell exact number or quantity.
Resource Breakdown Structure (RBS): This is another hierarchy structure used for projects. It helps you to group similar resources at a place that way you can build specialty teams with in project. It defines assignable resources such as personnel, from a functional point of view; it identifies "who" is doing the work. The total resources define the Top Level, and each subsequent level is a subset of the resource category (or level) above it. Each descending (lower) level represents an increasingly detailed description of the resource until small enough to be used in conjunction with the Work Breakdown Structure (WBS) to allow the work to be planned, monitored and controlled.
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The main goal for “Activity Duration Estimating” process is to provide effort estimation for all activities developed in during Activity Definition Process. Also know as Effort estimation, means how many hours/days are required to complete an activity. Duration is totally different than the work effort
- Effort: Just effort to complete an activity. We will not consider how many resources are working on this activity or when they are start or when they finish.
- Duration: The effort which was estimated above can be split among several resources or span across multiple days. For example, the effort for an activity is estimated as 24 hours. This is typically 3 working 8 hour days. If you assign 3 resources to perform this activity the duration will be just 1 day. Or you assign only one resource and estimate 1 hour work per day then the duration would be 24 business days which might even longer calendar days considering weekends and holidays.
There are several techniques are used in real world to estimate the effort. Out of all Expert judgment is the most important technique. Which is the core technique used in all other forms. Some subject matter expert should know what it takes to do it. PMBOK suggest few other techniques to refine the Expert judgment
- Analogous Estimating
- Parametric Estimating
- Three-point estimating
- Reserve Analysis
Analogous Estimating: Comparing to similar activity on the other project is the concept of this technique. This particular technique requires historical data to compare. In cases where there is no historical data, you would rely on other techniques and can’t perform Analogous Estimating
Parametric Estimating: Dependent on various parameters used for an activity. Multiplication of base unit of a parameter times of parameter size would give effort. For example 100 lines of code can be developed in 8 hours; then to develop 1000 lines of code it will take 80 hours. And if you need this in a week’s duration you will assign 2 resources.
Three-point estimation: Here you take pessimistic, optimistic, and realistic estimates for an activity. This approach can produce most close estimate than single Expert Judgment estimate. Normally average of these 3 estimates and Standard deviation are used.
Activity duration estimates are major outcome of above "Activity Duration Estimating" process
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Schedule Development
Schedule in simplest form is a plan for an activity or event. We make schedules for every event of our life. The major ingredients are Activity list and when those occur. Project Schedule development is no different than that. We identify when each and every activities occur. We defined activities and sequenced them in earlier phases. So we provide Calendar dates to all of those activities and that sums up to the project start and end dates too.
While developing Schedule development networking diagrams are very useful, this is a key input for this process.
Slack or Float: a float is amount of time you can use with out disturbing other planned activities. It tells how much of flexibility you have with in the project schedule. It is important to have flexibility. There are 2 types of internal slacks and one external slacks for any project.
Free Slack: The amount of time an activity can be delayed by not affecting successor activity.
Total Slack: The amount of time an activity can be delayed with out delaying the end of project.
Project Slack: The amount of time a project can delay with out delaying other projects with in program
In the above network diagram there are 3 possible paths
I) Start -> A -> C -> E -> END --- 5 + 3 + 2 = 10 DAYS
II) Start -> B -> D -> E -> END --- 4 + 6 + 2 = 12 DAYS
III) Start -> B -> D -> F -> END --- 4 + 6 + 6 = 16 DAYS
Out of those 3 paths Path III is the longest path which needs 16 days to deliver all 3 Activities in it. We call this one as Critical path.
In the above network diagram For E both D and C are predecessors. It need 10 days to complete B+D and to reach E. And it just takes 8 days for A+C to complete to start E. So even if gets 2 days of delay the start date of E will not be changed. So activity “C” has 2 days of Free Slack.
Path I) has 6 days of Total slack and still won’t impact Project’s end date.
The above process is called as Critical Path Method of Estimation. Observe that Activities on Critical Path doesn’t have flexibility that is ZERO SLACK.
Other tool provided by PMBOK guide is Schedule Compression.
The above network diagram has total of 6 activities and just 3 activities in longest path. Imagine a real project with many activities and longer critical path. Some times you might get delayed in early stages and would like to shrink activities in later phases. We call it as Schedule compression. We have to compress Critical Path activities only. We have 2 types of compression techniques.
- Crashing: adding more resources to any activity on Critical path activities.
- Fast Tracking: re-sequencing activities in the network diagram to gain time benefit.
Schedule in simplest form is a plan for an activity or event. We make schedules for every event of our life. The major ingredients are Activity list and when those occur. Project Schedule development is no different than that. We identify when each and every activities occur. We defined activities and sequenced them in earlier phases. So we provide Calendar dates to all of those activities and that sums up to the project start and end dates too.
While developing Schedule development networking diagrams are very useful, this is a key input for this process.
Slack or Float: a float is amount of time you can use with out disturbing other planned activities. It tells how much of flexibility you have with in the project schedule. It is important to have flexibility. There are 2 types of internal slacks and one external slacks for any project.
Free Slack: The amount of time an activity can be delayed by not affecting successor activity.
Total Slack: The amount of time an activity can be delayed with out delaying the end of project.
Project Slack: The amount of time a project can delay with out delaying other projects with in program
In the above network diagram there are 3 possible paths
I) Start -> A -> C -> E -> END --- 5 + 3 + 2 = 10 DAYS
II) Start -> B -> D -> E -> END --- 4 + 6 + 2 = 12 DAYS
III) Start -> B -> D -> F -> END --- 4 + 6 + 6 = 16 DAYS
Out of those 3 paths Path III is the longest path which needs 16 days to deliver all 3 Activities in it. We call this one as Critical path.
In the above network diagram For E both D and C are predecessors. It need 10 days to complete B+D and to reach E. And it just takes 8 days for A+C to complete to start E. So even if gets 2 days of delay the start date of E will not be changed. So activity “C” has 2 days of Free Slack.
Path I) has 6 days of Total slack and still won’t impact Project’s end date.
The above process is called as Critical Path Method of Estimation. Observe that Activities on Critical Path doesn’t have flexibility that is ZERO SLACK.
Other tool provided by PMBOK guide is Schedule Compression.
The above network diagram has total of 6 activities and just 3 activities in longest path. Imagine a real project with many activities and longer critical path. Some times you might get delayed in early stages and would like to shrink activities in later phases. We call it as Schedule compression. We have to compress Critical Path activities only. We have 2 types of compression techniques.
- Crashing: adding more resources to any activity on Critical path activities.
- Fast Tracking: re-sequencing activities in the network diagram to gain time benefit.
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Schedule Control has most important Tools and out puts for the projects which can be rolled up to Programs, Portfolios to Executive Management. That is Performance measurement and Variance analysis. This process iterative process through out the project execution. When changes are requested you have to monitor those using schedule Change Control System and recommended changes are suggested.
