Topics on the PMP: Parametric Estimating

Although the first word parametric might be new, estimating is something you have likely done before. Typically in planning any activity there is a level of estimating that occurs. When you go on your family trip to the beach, do you estimate how many times you will stop during your 8 hour drive? Or do you estimate how much money you will spend on gas to get to your destination?

Parametric estimating is a certain type of estimating, and one of a few different estimating techniques you will see on the PMP exam. Parametric estimating, like all other estimating techniques, helps you determine how long something will take or how much something will cost for a project.

This means for exam purposes you will find this topic associated with Time Management and Cost Management questions. Thus, the outputs of using parametric estimating are a complete schedule and budget for the project.

Let’s spend some time discussing parametric estimating and why a project manager might use it. As well let’s wrap up this blog by providing a few processes and tasks you might see in relationship to parametric estimating.

Parametric Estimating: Defined

Parametric estimating looks at how long a task will take to complete or how much it will cost, based on a relationship of variables.

Okay, what does a relationship of variables mean. I think it is easier to explain with an example. If we look at our cost for gas, from our example above, as our task – a relationship of variables would be miles (1 variable) per gallon (1 variable). We could determine exactly how many miles we get per gallon of gas, thus allowing us to more precisely determine how much gas would cost on our trip, because we could multiple the cost of gas and the precise number of miles we will get per gallon.

Parametric estimating is strictly used for quantitative measures. There needs to be a way to get to hard numbers, not just a qualitative estimate on how long something will take.

For example, as a project manager, you could quantify how long it would take to type a document if you could understand words typed per minute, and you knew exactly how many words would be used.

However, if you were assessing how long it would take to conduct an interview with someone, there might be less hard numbers you could rely on, thus using qualitative data.

For the purpose of parametric estimating, you can only use the quantitative measures.

Parametric Estimating: How it Relates

As I noted above you use parametric estimating within the Time and Cost management knowledge areas. You rely on items you produced in the Scope Management knowledge area, such as the work breakdown structure (WBS) to determine the most precise estimates.

Additionally, you use parametric estimating within the Planning process group, or project phase. You will sometimes reestimate in the Monitor and Control process group when the cost and schedule vary.

Remember as you study any topic for the exam, it is always important to understand how it relates back to the PMP Process Chart. Having a firm grasp of how all of this works together will allow you to excel on the exam.