Scheduling is planning or arranging work-items or events to complete at a specific time. This would depend on how much Work is to be completed by how many Resources in what time Duration. Their relationship is governed by the simple formula :
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Effort = Duration * Resource Units OR W = D * U |
Before, we understand the equation, let us understand the variables involved:
Work or Effort:
This is the effort (independent of a resource) required to complete a task. Typically it is described in man hours. Effort indicated is irrespective of holidays and resources since not all resources may be working equal hours. For example, a contractor may be working half days (4 hours). So, if a task with work/effort=20h, will take 5 working days for completion. However, a resource with full day working (8 hours) will finish it in 2.5 working days.
Duration
This is the elapsed working time (excluding holidays and any other non-working exceptions). If today is Monday and you say "I want this report by Friday" you are indicating a duration. It does not mean that the resource must spend all their time to prepare the report. The actual report preparation may take only 5 hours. In this case 5 hours is the effort but the duration is 5 days assuming that there are no holidays in between.
Units
Allocation is a way to have a resource work on multiple activities at the same time. It can be specified as a percentage of daily working time or as a total number of hours that a resource must spend on the task.
For example, if a resource works 8 hour every day and you allocate that resource for 50% on a task, you are effectively saying - spend 4 hours on that task daily. If you enter allocation in hours it indicates that the resource should work a total of those hours on a task. In the above example, you want a 10 hour task to be completed within 5 days. To achieve this you can either enter the allocation as 10 hours or 25%. Assuming that the resource works 8 hours daily 2 hours per day is 2/8 * 100 % or 25%. Celoxis will allocate 2 hours daily to the task so that they will complete the task by Friday.
Let's take a few more examples so see how it works. For all these examples, assume that the 1 Man Day = 8 hours and all resources also work 8 hours per day.
A task takes 2 man days (16 hours) to finish and you assign a resource to work full time (i.e 8 hours per day). How long would it take? If you said 2 days, you are right. Let's see if the equation matches with our expectation. In this case, effort = 16 hours and resource allocation is 1 (i.e 100%). So duration = 16 ÷ 1 = 16 hours or 2 days since each day is 8 hours.
Assume that you add one more resource to the task. How long would it take to finish the task? Again, it's quite easy - 1 day. Both resources will work 8 hours each and finish the 16 hour task in a day. Let's see again if the equation matches with our expectation. In this case, effort remains 16 hours while allocation is 1 + 1 = 2. So duration = 16 ÷ 2 = 8 hours or 1 day. Again it does. If both of you are told to work only 2 hours per day i.e 25% (2 ÷ 8), then how long would it take? Effort remains 16 hours while allocation is now 0.25 + 0.25 = 0.5. So duration = 16 ÷ 0.5 = 32 hours i.e. 4 working days.
There are many other factors that impact task scheduling. Let us look at them.A project schedule is the most important arsenal for the manager to deliver a successful project. It serves as a map of the route from project start to finish. It is a convenient form for monitoring and controlling project activities.
Scheduling essentially involves the following:
Identifying the tasks that need to be carried out,
Estimating how long they will take,
Sequencing them on the project's time line,
Allocating resources who will work on them.
Identifying the tasks: This is the first step and requires you to define the tasks, milestones, and other activities needed to complete the project. A useful aid to accomplish this is to create a Work Breakdown Structure (WBS). The WBS is a hierarchical decomposition of all the work in the project into manageable chunks. Creating this provides a better understanding of the work needed to complete the project.
Estimating: Once you have laid out all the tasks, the next step is to estimate how long they will take. There are a number of factors need to be taken into consideration when building estimates, such as supply and demand of each resource and how it relates to your specific project, any external client commitments that need to be honored, and the sheer nature of the work.
Sequencing tasks & allocating resources: The next step is to start putting these activities & their estimates in order. A Gantt chart is a simple and quick way to outline the entire project. You can group logical activities, create dependencies between tasks, and exhibit their relationship to each other. Finally allocate the resources who will actually perform the work in those activities.
This becomes your project schedule that combines project milestones, task durations and relationships.