Estimate Activity Resources is one of the 42 project management processes outlined in the fourth edition PMBOK®. It’s categorized as one of the six Time knowledge area processes, and one of the twenty Planning processes.
The purpose of this process is to examine the project activities and estimate what materials, people, equipment, and supplies are needed and how much is needed. The first thing to obtain is the list of activities and the accompanying information about them. These documents are called the Activity List and Activity Attributes, and they were created in the Define Activities process. Another input needed in order to make the estimations involving people is Resource Calendars, which is an output of the Acquire Project Team process that indicates when people are available. To actually estimate the resources needed for a specific activity, someone who is knowledgeable about the activity can provide an estimate—this is called Expert Judgment. Sometimes there are publications available that indicate what one should expect to pay for certain materials or labor. Utilizing these publications is called the tool and technique of Published Estimating Data. Lastly, an activity may need to be broken down into smaller components whose resource needs can be more accurately estimated. The total resources for these smaller components are simply added together to provide the overall resources needed for that activity. This is called the tool and technique of Bottom-Up Estimating. After the estimations are made, they become the major outputs of this process— Activity Resource Requirements and the Resource Breakdown Structure. Activity Resource Requirements is the documentation of the type and quantities of resources needed for each activity, and the Resource Breakdown Structure illustrates the needed resources in a hierarchical form based on the different categories of resources.