## PERT and CPM get Cozy

Project Estimation and PERT (Part 7): If you have been following the series on PERT, then you have developed a good understanding of probability and statistical concepts as applied to projects. In this post, we are going to see how Program Evaluation and Review Technique (PERT) and Critical Path Method (CPM) come together in estimating the total project duration. PERT is a probabilistic method, whereas CPM is deterministic. PERT estimates the activity durations based on probability, whereas CPM assumes that the activity durations are fixed. We’ll take a sample project and work through it to understand the concepts.

## Probability and Statistics in Project Management

Project Estimation and PERT (Part 6): So far we have learned about the basics of PERT, how PERT is used to estimate activity completion time, and how the PERT formula was derived. We know that a project manager has to wear several hats. In this article, we are going to wear the probabilist and statistician hats and review the basic concepts of probability and statistics relevant to project estimation. It is certainly “out of scope” as far as the PMP exam is concerned. But if you ever wanted to learn the basics of random variables, distributions, mean, variance, standard deviation etc., without sacrificing a lot of precious time, then this article is just for you. I think it will give you the necessary foundation for understanding the concepts of project estimation and bring you one step closer to implementing theory into practice.

## The Magical Formula of PERT

Project Estimation and PERT (Part 5): We saw the formulas for PERT estimate, variance and standard deviation of an activity duration in study guides, and accepted them like Newton’s three laws of motion. Did we try to figure out how those formulas were derived? Do we know the underlying assumptions? Is there a magic in these formulas that allows them to predict the outcome of something as unique as a project? Can these formulas predict the project outcomes accurately? Are these formulas actually being applied in the real world? We’ll find some answers in this article and remaining in the upcoming ones. But please be forewarned - if you are math-averse, this stuff may divide your head by zero!

## Say Hello to PERT

Project Estimation and PERT (Part 4): In the previous article, we learned about the advantages of 3-point estimation. In this post, we’ll carry the concept forward and talk about a special type of 3-point estimation technique called Program Evaluation and Review Technique (PERT). PERT was developed jointly by the U.S. Navy, Lockheed Martin, and the consulting firm of Booz, Allen and Hamilton working on the Polaris nuclear submarine project, in the 1950s. PERT is one of the most commonly used techniques used along with Critical Path Method (CPM) to estimate the minimum time needed to complete a project. Let’s learn more about PERT in this post.

## The Power of Three in Project Estimation

Project Estimation and PERT (Part 2): An estimate by definition is a guess, albeit an educated one. If estimates had to be always accurate, then they wouldn’t be called estimates. Every task involves an element of uncertainty or risk. A good estimate incorporates the uncertainty or risk involved in the task. This article is a prelude to a series on project estimation using PERT. The basis of PERT is 3-point estimation, which we'll review here.

## Get Intimate with PERT

Project Estimation and PERT (Part 1): Most PMP study guides and training programs offer very similar and limited information on Program Evaluation and Review Technique (PERT). The information is usually sufficient to pass the PMP exam, but isn't detailed enough to get a good understanding of the topic, nor does it offer much practical value on real projects.

I have received numerous requests from people asking me to explain this topic in more depth. So I've spent past several weeks researching this topic. I won’t say that I’m an expert now, but I hope to share the knowledge and learn something from you in the process. As usual, I'll try to present a detailed yet simplified explanation.

Before I go further, let me warn you that some of these articles may be far-far beyond the scope of the PMP exam. These articles are meant for those inquisitive souls, who not just want to pass the exam, but also learn something useful and practical along the way.