Tweet

Some Dangers of PERT Charts

Guest post by: Robert Whipple

Article Overview: Many companies use PERT charts to track the progress of projects. These charts show the major milestones in complex projects and develop a “critical path” through the ones that must not slip or the entire project suffers. Depending on your job, you may be exposed to these. They are used extensively in military projects and large construction projects. The more sweeping and complex a project is, the more useful a network representation can be. There are some precautions that I will describe here.

Some Dangers of PERT Charts

The formulas and equations for constructing project networks are all straight forward. Anyone who can add or subtract can master the math. However, the complexities of prerequisites and parallel paths can become confusing. If you are not experienced on constructing networks you may do a good job of addition but miss some of the key logic. That would make your network less useful or even misleading. I think it is best to leave the creation of project planning networks to experts who do it all the time. Even if you have a facilitator helping with administration of a network, there is a danger of assigning too much credibility to the numbers if we forget their origin. Here is a story from my background to illustrate the point.

Early in my career, I worked on a Defense related project. During the cold war I worked on a program to keep track of what the Russians were doing. The reason I can write about it now is that the material has been declassified, and there have been several articles written about the program. I was an engineer responsible for testing one of the key components of the system.

Every day a guy named Bart would arrive at my desk sometime in the morning. He would sit down and start chatting about this or that. He was an alcoholic, so he had lots of drinking stories to tell. He would then start asking me questions about work. He would ask things like, "When do you think model 17 will be ready for final testing" or "how long will it take you to get model 22 ready for vibration testing?"

Bart was what they call an "expeditor." His job was to pump all the engineers for information on the timing of events and construct a PERT chart showing critical path for each model. This was all he did. He would update the PERT Charts daily and feed them back to upper management so they would have a good feel for how the complex projects were progressing. This all sounds pretty good until you examine the behaviors more closely.

Bart was viewed by the engineers as a pest. He would show up when people were busy and expect them to drop what they were doing to give him answers. Often, they would just make something up that sounded plausible in order to get rid of him. Another issue was that the engineers did not want to "paint themselves into a corner," so they would give estimates of completion dates with lots of padding so they would not be embarrassed later on. It was sort of a game to the engineers. The result was that the PERT charts were not a good reflection of reality. The printouts looked official, but it was "garbage in- garbage out."

The moral of this story is to be careful when gathering data for a project network. Make sure the information going into the model is accurate and not biased with someone's ulterior motive.

Another issue is the psychological impact of "slack" time. Most people have a tendency to let down their intensity if they know there is slack time in the schedule. It is the same reason why most students start their papers a day before they are due. It is not a healthy thing to do, but the majority of humans have a habit of procrastination.

If someone is aware that there are two weeks of "slack" time in a schedule, then the work is likely to be put off. That may cause an item that was not on the critical path to actually hold up an entire project simply because the slack time was advertised.

PERT Charts are useful for project planning, but you have to go in with your eyes open to the dangers inherent in these representations.

Related Articles
  Hitting Deadlines: Master the Art of Estimating Time
  Add Power to your Presentation through Effective Use of Visuals
  QVinci for QuickBooks - The Custom Dashboard and
  Things to Know About a Small Business Credit Card
  5 Ways To Improve Your Stock Market Results
  Gold Reaching All-Time Highs!
  Price and Volume Analysis-The Key to Making Big Money
  Steps To Take At Home
  Presentation Power - Does Your Audience Hate To Read?
  Trade Commodities For Big Profits
  Analytics- A Marketing Managers Friend or Foe?
  5 Things you need to know before start online forex trading
  Choosing the Best Chiropractic Software for your Practice Style
  Learning to Win in the Stock Market
  How to Build Trust and Credibility
  12 Steps to Implementing Anything in Your Business : Step Six: Use Plans, Schedules, Budgets and Controls
  \"Canned Sales Presentations\" Just Dont Work Today
  Is Becoming an Amazon.com Bestseller Worth Anything?
  Searching the scopes of iPhone application development for stock trading
  Taking the Risk of Loving

Article Tags: critical path, Leadership, military, PERT Chart, planning, slack time, Trust



Related Forum Posts


Share this article with your friends. Fund someone's dream.

Leave a comment below or share on the left and you'll help support entrepreneurs in Africa through our partnership with Kiva. Over $50,000 raised and counting - Please keep sharing! Learn more.

Newsletter

Get advice & tips from famous business
owners, new articles by entrepreneur
experts, my latest website updates, &
special sneak peaks at what's to come!

Name:
Email:

Popular Articles

Fear Factors in Small Business: Sales & Marketing

How To Master The Ins and Outs of Google+

Understanding Influence

Suggestions

Email us your ideas on how to make our
website more valuable! Thank you Sharon
from Toronto Salsa Lessons / Classes for
your suggestions to make the newsletter
look like the website and profile younger
entrepreneurs like Jennifer Lopez.