Project Management Foundations - Estimating and Loading Resources

May 3, 2011 | Author: PM Hut | Filed under: Scheduling

Project Management Foundations - Estimating and Loading Resources
By Steve Hart

One of the common pitfalls I often run across when reviewing project schedules is inadequate attention or diligence around the area of resource planning. Improper planning in this best practice area often leads to project schedules and budgets that may not be reasonable or manageable. The following summarizes the high level best practice areas associated with resource planning:

  • How to estimate the resource requirements for schedule activities.
  • How to load the resource assignments and work effort estimates into the project schedule.
  • How to perform resource usage analysis, and resource leveling techniques.
  • How to create the resource plan utilized to finalize resource assignments, and provide a key input to create the project budget.

For purposes of this article, I will focus on the first two — estimating resources and loading the resource assignments into the project schedule.

Resource Estimating

There are two techniques for resource estimating – bottom up & resource allocation. Both techniques are valid, and each are more effective than the other in specific situations.

Bottom up Estimating

The following steps describe the mechanics of this technique:

  • Work with the team to estimate the work effort (hours) for each resource assigned to the activity.
  • Enter the hours for each resource assigned to the activity within the Project Management tool.
  • The Project Management tool computes the allocation % for the activities (based upon the hours and duration assigned to the activity).

When is this technique most effective:

  • The activity is complex, and the team needs to spend time to understand the details associated with the activity.
  • Experience with other projects is based more on actual hours of work effort.
  • Precision of the work effort is very important, and is worth the time to create a more accurate schedule.

Here is an example of how this technique works:

Bottom-up Estimating

Resource Allocation

The following steps describe the mechanics of this technique:

  • Group activities based upon allocation of resources (may be one to one, but more likely will have activities with the same allocation over some period of time).
  • Assign allocation % for each resource assigned to the activity in the Project Management tool.
  • The Project Management tool computes the number of hours of work effort for the activities (based upon the allocation % and duration estimated for the activity).

When this technique is most effective:

  • Details of the activity are not known, and therefore it is the duration estimate that is driving the resource estimates
  • Experience with other projects is based more on “how long it takes” vs. “how many hours of work”
  • Precision of the work effort estimates is not as important as developing a reasonable schedule

Here is an example of how this technique works:

Resource Allocation

As depicted in this example, both techniques arrived at approximately the same resource needs (this certainly will not always be the case). However, the approach to arrive at the resource needs was very different and highly dependent on the situation and information available. For each set of activities within the schedule, it is important to decide on the appropriate approach to estimate and assign resources, and then gather the information required to determine resource requirements. In many cases the project manager will use a combination of the two approaches (#1 for more complex work effort driven activities, and #2 for more duration based activities).

Resource Loading

Once the resource estimating process is complete, the mechanics of loading resources into the schedule is very straight forward. From the resource tab on the individual task, or from the resource column in the Gantt view (assuming you are using MS Project as your PM tool), the resources are added in the following manner (depending upon the approach selected):

  • Approach #1: Select the resource, enter the hours in the work column, and the % allocation will be computed.
  • Approach #2: Select the resource(s), enter the % in the units column, and the work hours will be computed.

Another key element associated with the resource loading process is the task type set-up for the activity. Use of different task types impacts the way the units (%), work and duration are re-calculated when any of these elements are changed. I always recommend use of fixed duration with an effort driven option as the default set-up. It allows work and units to fluctuate as you modify the timeline (duration). The table below describes the different behaviors within the project schedule, based upon the task type:

Fixed Units - Fixed Work - Fixed Duration

When loading resources, a good check that you have the activities broken down to the appropriate level is whether or not you have direct accountability of resource assignments. If you have a lot of tasks with 2-3 people with a 10% allocation, you may not have the activities broken down to the appropriate level.

You want to avoid falling into the trap of loading activities into the schedule that are “indirect” in nature that are merely loaded to reflect usage of individual’s time on the project. Try to keep the schedule focused on “direct” project activities. There are other ways to reflect commitment to the project without putting “noise” in your schedule.

Resource Estimating and Loading Best Practices

In summary, the following are the best practices associated with the resource estimating & loading processes:

  • Use the resource estimating and loading approach that best fits the type of activities that are being planned
  • Do not add “noise” into the schedule by attempting to account for all hours expended on the project (activities in the project schedule should be limited to “direct” activities).
  • Set-up the schedule activities in a manner that drives the appropriate behavior when loading resources into the project schedule. I recommend fixed duration as the task type.

Steve Hart, PMP is the Practice Manager responsible for project leadership & delivery services for the Cardinal Solutions Group in the RTP area. He has 25 years of project management and technical leadership roles, and has developed an extensive practical knowledge that spans a wide variety of industries, and project delivery approaches. Steve recently transferred to the North Carolina Chapter of PMI from the Dayton Ohio PMI Chapter, where he was active as the editor of the chapter newsletter, and PMP certification instructor. You can read more from Steve Hart on his blog.

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[...] a previous article, I talked about resource loading your project schedule (estimating the resource needs, and loading [...]

Project Management Foundations - Performing Resource Analysis and Creating the Resource Plan - PM Hut wrote on June 2, 2011 - 8:12 am | Visit Link

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