Once the activities required to complete that project have been identified and coordinated into a logical sequence, the next step is to identify the resources required to undertake them. Activity resource estimating is the process by which these resources are identified and quantified. The types of resources will vary from project to project, but may include skilled personnel, money, facilities and equipment. Think about a recent project you have worked on and try to identify the different types of resources used. It is likely that you have identified more than you may have originally thought. Managing and coordinating often competing resources can prove challenging to even the experienced project manager. It is this process, activity resource estimating, that should provide the project manager with the advance knowledge of their requirements before commencing the project. Indeed, activity resourcing can often determine whether a project will proceed. For example, if you are working on a construction project and there is a global shortage of concrete for the next six months, it may be decided to delay the project or cancel the project altogether.
There are six inputs to activity resource estimating:
These six inputs can be divided into two groups: the first two tell you what is available to you; and the remaining four are what you need to complete the project. Activity resource estimating is all about matching what you need to what is available.
Resource availability is, simply, information concerning the availability of the resources required for the project. This may include the type of resource, its location and its availability. Your key programmers might be available for the project, but when are they on annual leave? The scope and length of the project will limit the extent to which the information concerning the resources will be valid. Early requirements would be relatively easy to pinpoint in comparison to requirements in two years' time.
Tools and techniques
There are five tools and techniques available to the project manager for activity resource estimating:
More than enough ink has been spilled on expert judgement and the limitations of project software, so we will move on to examining the remaining three.
This technique looks at the resource requirements and attempts to determine what alternatives there are to achieve the same result. This could mean choosing between a highly skilled machinist who will do the job in a week but is available for only two weeks a month after the output is required, against a novice but capable machinist, who is available now and will produce the product, but the quality might not be as high as that of the experienced person.
Published estimating data
Project managers can also make use of published estimating data produced by other organizations. These provide regularly updated production rate and unit costs of a wide range of resources, such as trade labour, raw materials, equipment, and so on.
Bottom-up estimating is a technique that can be used when the activity cannot be fully resourced as is. It involves further decomposition of the schedule activity so that the component tasks can be individually resourced. The use of bottom-up estimating can be seen as an iteration of the activity definition and activity sequencing process groups to achieve the required level of detail. In reality, this iteration will apply to only a few activities and, except in extreme cases, will not require a re-examination of the whole plan.
There are five outputs from activity resourcing:
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