A pert myth

PERT (Program Evaluation and Review Technique) is a stock standard method to manage project schedule risk. It is taught (or at least mentioned) in just about every project management course. PERT was first used (and is considered to have originated) in the Polaris project, and is often credited as being one of the main reasons for the the success of that endeavour. The truth is considerably more nuanced: it turns out that PERT was used on the Polaris project more as PR than PM. It was often applied “after the fact” – when generating reports for Congress, who held the project purse-strings. This post is a brief look into the PERT myth, based on sources available online.

An excellent place to start is Glen Alleman’s post from 2005 entitled, Origins and Myth of PERT¹. Glen draws attention to a RAND Corporation publication entitled, Quantitative Risk Analysis for Project Management – A Critical Review, written by Lionel Galway. The paper is essentially a survey of quantitative risk management and analysis techniques. The author has this to say about PERT:

…PERT was a great success from a public relations point of view, although only a relatively small portion of the Polaris program was ever managed using the technique. And this success led to adaptations of PERT such as PERT/cost that attempted to address cost issues as well. While PERT was widely acclaimed by the business and defense communities in the 1960s, later studies raised doubts about whether PERT contributed much to the management success of the Polaris project. Many contended that its primary contribution was to deflect management interference by the Navy and DoD (Department of Defense) by providing a “cover” of disciplined, quantitative, management carried out by modern methodologies…

Then, in the conclusion of the paper, he states:

…While the Polaris program touted PERT as a breakthrough in project management, as noted above not even a majority of the tasks in the project were controlled with PERT. Klementowski’s thesis in the late 1970s, although limited for generalization by the sampling technique, showed less than a majority of organizations using CPM/PERT techniques. And the interviews conducted for this report revealed a similar ambivalence: respondents affirmed the usefulness of the techniques in general, but did not provide much in the way of particular examples…

In a footnote on page 10 of the paper, the author draws attention to Sapolsky’s book The Polaris System Development: Bureaucratic and Programmatic Success in Government. Among other things, the book describes how the use of PERT on the project has been grossly overstated. Unfortunately the book is out of print, but there is an excellent review of it on Cadmus. The review has this to say about the use of PERT on the Polaris project:

…SPO (Special Projects Office) Director Vice Admiral William F. Raborn pushed PERT mercilessly. The colorful PERT charts impressed everyone, and coupled with the nature of the project, they exuded management “sex appeal.” This kept other DoD poachers at bay and politicians off SPO’s back. Other government services became so enamored with PERT, they quickly made it a requirement in subsequent contracts.A more objective assessment of PERT is that the network analysis² is the major benefit. PERT can reduce cost and time overruns, and make its practitioners look like better managers…

The Royal Navy knew of the over-inflated success of PERT when it embarked on its own Polaris program in the 1960’s. The Royal Navy deliberately adopted PERT, essentially to keep Whitehall, Parliament and other critics away from their project. It worked just as well for the RN as it did for the USN
…

I found the accounts of PERT presented in these sources fascinating, because they highlight how project management history can be so much more ambiguous (and messier) than textbooks, teachers and trainers would have us believe. Techniques are often taught without any regard to their origins and limitations. Thus disassociated from their origins, they take on a life of their own leading to myths where from it is difficult to separate fact from fiction.

Footnotes:

¹ Glen Alleman also discusses some limitations of PERT in this and another post on his blog.

² Network analysis refers to task sequencing (precedence and dependencies) rather than task durations.