Estimate Activity Resources for the Project – People & All Else

Estimate Activity Resources Estimating Activity Resources is the process of figuring out what type of resources, and how much of each type of these resources would it take to perform the activity.

Resources could mean people, hardware, software, materials, tools, equipment, supplies, machinery, or anything that is used to execute an activity.

Where shall we start?

Resource management plan comes from Plan Resource Management process. This plan contains the approach and guidelines on how to identify and estimate quantities of resources required for activities, so this input is going to help.

Scope baseline contains scope statement, Work Breakdown Structure, and the WBS dictionary – information about the work packages.

Activity list and activity attributes come from Define activities process, and they give you everything you need to understand about an activity in order to estimate resources. We need to know skills needed, number of people with each of these skills, equipment, machinery, tools – all types of resources, so we can then look at the duration they need for.

You would need resource calendars – a document that has information about availability, capability, and skillset of resources during the length of the project. With this you can identify and tag appropriate resource(s) to each activity in the list.

Resource calendars can unearth constraints – what if you needed a Database Architect for your software project and the only person available is assigned to another project and not available until after the design phase? You will need to figure out alternatives – bring in a consultant, hire someone from outside, or outsource the work?

Cost estimates keep us in within the boundary – being able to know how much money we get to spend helps us decide what quality of resources we can plan for.

Risk register is another important document for reference during this stage. Resource related potential risks already identified during planning stage must be understood while estimating resources for activities.

Since this is sort of a standard activity, you might already have sample documents from earlier projects. Also some caution and tips from the lessons learned there. Moreover, there may be templates that your organization mandates that you use on your project. There could be specific policies for acquiring resources from outside the company. All these are available in organizational process assets.

And finally, you will need some help from enterprise environmental factors – for things such as existing resources in the company, their competencies and their availability.


Expert judgment means getting help from people who have already executed similar projects, or people who have the necessary training to gain the knowledge. In many a cases you may do most of the work yourself but there could be special skill needs and you would need advice on alternates, and an expert can help.

Analogous estimating

This is pretty straight forward. You look at similar activities with similar resource category and types from similar type of projects executed earlier and base your estimates on this information. This method is most useful when you don’t have enough information in the current project and you are doing progressive elaboration.

This technique takes lesser time but at the cost of being less accurate. Best fit for this is the case when current project and the team is similar to the previous project and its team. Hence, it is better to use this technique in combination with other tools and techniques.

Parametric estimating

This is an activity durations estimation technique where statistical techniques are used to calculate cost or duration values for activities based on data from similar earlier projects. You put in numbers, or parameters, into a spreadsheet or software that uses data from other similar past projects to calculate estimates.

For instance, per historical data it takes a worker one hour to dig 50 square ft. of land using a certain earth digging equipment. Using this data John calculates that for his house project of 800 square ft. it takes about 16 hours (or two 8-hr days) to dig the earth.

Parametric estimating method gives more accurate results than analogous estimating technique provides.

What do you do when an activity seems to involve too much of work for you to comfortably estimate on resources?

You may have some idea but not very sure about its accuracy. You could then use a technique called bottom-up estimating. This is pretty simple – you break down activity into smaller pieces, to the level where estimating resources is easy. Then you roll up the estimates to the level of original activity. This will be your resource estimate for the activity.

Alternatives analysis refers to figuring out alternate types of resources (architect or senior engineer?), skill sets (expert or semi-skilled?), equipment (big or small?), means of work (manual or automated?) and then weighing in the right choice based on factors such as cost, time and quality associated with each of them.

Published estimating data – Many a projects can use standard resource information in the industry, based on countries or specific geographic locations. This industry information is typically published in trade journals, websites, government publications or periodicals. In construction industry, this could be time taken to perform different construction activities. Project managers can utilize some of this information to estimate what kind of resources they can assign to activities.

Most often than not you would use a project management software, such as Microsoft Project or any open source web-based software to plan resources for activities. These software packages provide ways of playing with combination of resources and select the optimal combination.

You may be using one or more of above tools and techniques for estimating resources, and the schedule plan would have references to recommended tools and techniques.

You’d end up Estimating Activity Resources, of course

This is the document where you list each activity, type and quantity of resources required, their availability, assumptions made, constraints discovered, and dependencies found. This document is called Activity Resource Requirements.

Each estimate has to be backed up by logic and reasoning, right? So you create basis of estimates document as well. Look at it this way, this will be hugely useful if estimates need to be revisited at a later point in time, or the original members that estimated are not available.

Resource breakdown structure (RBS) is pretty similar to Work breakdown structure (WBS) and is the other output from this process.

With this information you could roll up activities till work package level, and see what resource utilization figures look like.

Whenever you refer to project documents you may discover updates to those based on the outcome of this process. Documents such as activity list, activity attributes, risk register are some of the documents prone to be updated during this process.

Estimate Activity Resources and Estimate Costs processes are closely related, in that, when resource costs change they will impact your cost baseline. For instance, if you consider one of the tasks need specialized skills that your team does not possess you may need to hire a consultant or send someone from the team for training. Both these options cost money and need to be factored in project costs. Therefore, project manager will go back and forth between these processes to make adjustments.

With the activities identified from WBS, and sequenced, and durations estimated, with resource estimated now, you can go ahead and work out the schedule!

Next, in resource management knowledge area we move to acquire the resources we need!

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