Schedule

Schedule

• A project schedule defines the timeline of the tasks to be completed
• Coordinate the tasks to be done

Schedule Planning

• Schedule planning involves the following:
  • activity definition (what to be done)
  • activity sequencing (the order it is done)
  • activity duration (how long it take)

Activity Definition

• The foundation of developing a project schedule is to list out the list of activities to be carried out
• Activity definition is the process of breaking down the deliverables in the WBS to smaller manageable task
• These activities cannot be too detailed till it's unmanageable nor too brief as it will be difficult to do estimate on a vague task

Activity Sequence

• Activities are not carried out at the same time in parallel
• Activities are dependent on each other usually
• Activity sequencing is the process of identifying the dependency relationship, type of dependency and specific relationship

Type of Dependencies

• A dependency describes the relationship between two tasks
• There are 3 types of dependencies
  • Mandatory dependency is created by he natural of the type of work to be done (e.g. a tyre cannot be tested until it is manufactured)
  • Discretionary dependency is something the project team choose to impose (e.g. targeted date of completion)
  • External dependency is a due factor outside the project (e.g. date of shipment of raw materials (latex) taking two weeks to arrive)

Dependency Relationship

• Once a dependency is identified between two tasks, we need to determine what dependency relationship it is
• Some basic knowledge:
  • A predecessor is a task that occurs before a particular task
  • A successor is a task that occurs after a particular task
  
  • Activity A is a predecessor to Activity B
  • Activity B is a successor to Activity A

4 Possible Dependency

• Tasks maybe scheduled in parallel or successor task may have to wait till predecessor is completed
  • Finish to Start
  • Start to Start
  • Finish to Finish
  • Start to Finish

Dependency Types



Finish to Start

• Successor task cannot start until the predessor task has finish
• Most commonly used
• Example: Server has to be received before software can be installed

Start to Start

• The start of the successor task depends on the start of the predecessor
• Example: Once testing on product starts, user manual documentation can start too

Finish to Finish

• The finish of the successor task depends on the finish of the predecessor
• Example: Finishing the product depends on the completion of the user manual

Start to Finish

• The finish of the successor task is dependent on the start of its predecessor
• Seldom used

Network Diagram

• Once we determine the dependency relationship, we can create a network diagram to represent it
• The diagram below shows a sequence of tasks with finish to start dependencies

Activity Duration Estimate

• Duration of task can be in terms of calendar days or work days (e.g. 1 week can be considered as 7 calendar days or 5 working days)
• Techniques to estimate duration of a task can be via:
  • Analogous estimating or top-down estimating
  • Expert judgement
  • Quantitatively based durations

Analogous estimating

• Analogous estimating is also called the top-down estimating
• Use durations from previous project done before
• Used at early stage of project when available information is limited
• Typically less accurate

Expert judgement

• Expert judgement used by the person who is most familiar with the work
• Estimates will be more accurate by the person who will be performing the task
• An experience person might take only two days to write a particular problem but a person with lesser experience, will take more time

Quantitatively base durations

• Quantitatively based durations are used when there is a formula to gauge durations
• Example: If you know that it takes 1 day to bury 5km of cables, 50 km of cable will take 10 working days to complete

Network Diagram with Task Duration

• Once we determine the duration for each task, the information can be included in the network diagram

Critical Path

• Allows us to determine the duration of the whole project
• Allows us to determine what is the critical path
• A critical path is defined as the longest path through the project sequence of tasks
• Determines the duration of the project
• Critical as in affecting the time; might not be the most important task

Critical Path Analysis

• Critical path analysis-is a network diagramming technique used to predict total project duration
• The longest path or the path containing the critical tasks is what's driving the completion date for the project

Who's Stuck with the Gorilla This Week?



What does the Critical Path REALLY mean?

• The critical path shows the shortest time in which the project can be completed
• If one or more of the activities on the critical path takes longer than planned, the whole project schedule will slip unless the Project Manager takes corrective action
• Example: Apple computer team members put a stuffed gorilla on top of the cubicle of whoever was in charge of a critical task, so they would not distract him or her

Critical path - time and risk

• Late critical path activity equals late project completion
• Identify critical path activities early and monitor closely
• Create prevention and contigency plans
• Monitor activities that could enter the critical path

Critical path calculation

• To determine the critical path, there are 3 steps
  • Forward pass
  • Backward pass
  • Float/Slack

Forward pass

• It is called forward pass because you are working from the left to the right of the network diagram
• Calculates:
  • Early Start - Earliest date an activity may begin. This is the date when the predecessor tasks ends
  • Early Finish - Earliest date an activity may finish. This is the date when the task starts plus the duration of the task

Backward pass

• It is called backward pass because you are working from the finishing end of the network diagram (right to left)
• Gives you the
  • Late Start - Latest date an activity may begin
  • Late Finish - Latest date an activity may finish

Slack/Float

• Slack/float is the flexibility an activity start date has without affecting the project completion date
• The sequence of tasks along a critical path determines the duration of the project. These tasks have zero (0) float as any delay in the tasks will affect duration (thus end-date)
• Calculate slack using dates for each task by subtracting the early start from the late start or early finish from the late finish (e.g. LS-ES or LF-EF)

Source: PMP, Prince2