PERT and Parkinson's law

which rules perform best?

Ed. Note: The discipline of Project Management has been attacked for a seeming over-reliance on various planning and control techniques — particularly PERT and CPM. Indeed, in past issues of PMQ several cautions in this regard have been published. In this vein, the following article is offered for your delight … or dismay.

Everybody knows Parkinson’s Law. Nearly everybody quotes favorite cases to warn, amuse, or arouse. The Parkinson phenomenon is recognized by managers and newsmen, by bureaucrats and their critics.

The readers, even the youngest ones, can’t help knowing about PERT. Some taught it, others studied it; some practiced the art, others were practiced upon.

Parkinson’s Law and PERT were launched internationally, and independently, in 1957. Few afficionados of either know that Parkinson and PERT address the same subject. This close kinship deserves a popular exposition. As the two recede into history and merge into the common stream of managerial lore the perspective gained makes this task urgent.

The disastrous “plumbing” enterprise of the century was planned and launched without PERT, an omission unthinkable ten years ago when the famous Watergate complex was being perted. Some observers predict a revival of PERT at the highest levels. A President, or a candidate for the office, would employ a crew of perters in charge of an impeccably loyal pertmaster.

The Appendix is a refresher course in PERT for senior management. Suitable for self-study, it makes this paper self-contained.

CONTENTS   1. Parkinson’s Law


3. A Philological Digression

4. Parkinson vs. PERT

5. Appendix: A Refresher Course in PERT for Senior Management

1. Parkinson’s Law

The first, or major, of Parkinson’s Laws, the Law, is encapsuled in the opening sentence of his first book on management: “Work expands so as to fill the time available for its completion.” (Parkinson’s Law and Other Studies in Administration, by Professor C. Northcote Parkinson, 1957, Houghton Mifflin). If a senior civil servant is entrusted with filling out a form within fourteen days, a task requiring a concentrated effort of 30 minutes, it’s unlikely that his coordinator’s assistant’s secretary will complete the typescript prior to the deadline. Conferences, rulings by legal counsel, policy analyses may reduce the Parkinson Gap of a fortnight minus half an hour down to zero or worse. New personnel may be added, overtime authorized.

The Law applies to individuals, teams, organizations. It holds for the civil service, armed forces, foundations, corporations, universities. Conscious and unconscious factors are at play. There is the defensive desire to appear busy when there is no work backlog. There is the yearning to be fruitful and to multiply subordinates. There is the general tendency to just procrastinate.

Parkinson explains why the useful work done by the civil service depends so little on the numbers employed, on overtime policy, vacation schedules, or retirement practices. The compound growth rate of a bureaucracy or its feverish activity are not indices of its effectiveness. The Law provides a powerful argument in favor of reducing its working time down to three six-hour days a week in lieu of a 5% salary increase: the taxpayers save 5% but lose no services; the bureaucrats gain leisure, and time for outside employment; and the fuel expended on commuting to work is cut by 40%.1 Inducements to early retirement from the civil service or armed forces are consistent with this reasoning. The pension increase is high enough to make an employee retire but is less than his wage.

Parkinsonian Propensity

This is the percentage of the payroll or wage lost to the Parkinson effect. The Personal Parkinson Propensity, PPP, applies to each employee and varies from the uncharacteristic zero to 100% (full-time sinecure, total featherbedding) or more (sinecure with overtime). Each organization has its Bureaucratic Parkinson Propensity, BPP, its percent of time lost to the inexorable Law. Some researchers claim that the rate of growth of a bureaucracy is proportional to its BPP which is seldom less than 35% and can exceed 90%. Conversely, the BPP can be deduced from the expansion of personnel, a fact important in historic studies of productivity.

Finally there is the Gross National Parkinsonian Propensity, GNPP, the percent of all losses which are due to the Parkinson effect. Some scholars believe the GNPP has been growing at about twice the rate of the Gross National Product, GNP, in recent years. Such growth cannot continue indefinitely. I agree with other eminent authorities that the growing GNPP has been a prime cause of inflation.

Some economists and social scientists are more concerned with differentials in Parkinsonian Propensity among various industries, skills, and locations. If everybody’s Personal Parkinson Propensity were exactly 50% this would amount to a working week reduced by 50%. Each employee would lose as consumer what he would gain as producer.


Many consultants recall wistfully how PERT was spreading in the late fifties and early sixties with the vigor and faith of chain letters and pyramids. Instruction in PERT ranged from briefings lasting fifteen minutes, including a question period, up to four weeks total immersion courses (workshop, case studies, biographies of the promoters and Founders). Every other attendant, so it seemed, would be emboldened to orchestrate his own proprietary course with all the celerity allowed by the post-office. The PERT trademark, a few circles connected by confidently poised arrows, was a common feature of third-class mail.

PERT’s spread exceeded by far humanity’s net reproduction rate and could not be sustained for long. The supply of teachers and consultants in PERT kept growing inexorably, the ranks of students and potential clients kept on shrinking. The PERT industry reached its peak around 1965 in the United States and in 1968 elsewhere. No precise data have been collected by the Bureau of Census or by private surveys.

Fortunately, PPBS (Program Planning and Budgeting Systems) took off, when PERT became too commonplace, with the help of former PERT manpower. Some claim that PPBS is a continuation of PERT by other, higher scaled, means. Now PPBS is fading away and some have it that it’s being superceded by Management by Objectives. (All are instances of “management by cliche,” according to wags.)

Following a wide custom I use the term “PERT” in its broad sense of Schediography, Network Planning, or Reticular Management, as it is known in scholarly contexts. Numerous variations of PERT, each based on a flowchart of circles and arrows, have been promoted. Some of PERT’s keenest intellects used to debate around 1960 the reletive merits of arrows representing activities or events.

PERT bestows upon its initiates instant management expertise in most diversified enterprises. This is its wonder and glory. A modest skill in freehand drawing of arrows and circles, a glossary of two dozen trade terms or so (dummy, path, activity, critical, pessimistic, optimistic, float, slack, total, free, independent) would admit an enterprising self-assured practitioner into many a corporate board room. PERT provided a launching pad for numerous administrative and managerial careers.

PERT has carried on in the aerospace industry, in construction, transport, research and development, marketing campaigns, even in the plotting of detective novels — or so it was rumored. PERT was proposed for planning and scheduling the therapy and instruction at the Masters-Johnson Clinic in St. Louis.

3. A Philological Digression

“PERT,” one of many competing brand names, early in the history of the movement began to stand for all network planning. Its name turned into a common noun as did “aspirin,” a product of comparable prevalence in the sixties. (“PERT is management’s aspirin,” used to quip PERT’s deprecators.)

This may appear strange. Wasn’t CPM (Critical Path Method) at least as common? What about the dozens of other carefully composed acronyms? Why not “schediography,” “network planning,” “reticular scheduling” for colloquial and generic usage? PERT’s acceptance isn’t due to its technical superiority.

“PERT” is morphologically most flexible. There are the adjectives pertorial and pertable, the adverb pertwise, the nouns, perter, pertress, pertor or pertrix, in legal and contractual contexts, and pertee. (Notice the lower case lettering.) The verb can be transitive: Dick and Jane are perting the construction of a nuclear power plant. It can be used intransitively: perting passionately; compulsively, with gusto. The verb can be reflexive: Counsellor, pert thyself! (Saasor, perte te ipsum; perteo, pertere.) A pertor can pre-pert, post-pert, re-pert, refuses to de-pert. He can sell a millions dollars’ or a nickle’s worth of pert (a collective noun here.)

Try similar constructions with CPM. RAMPS, or other lables you might recall.

“Pertocracy,” a term designating the influence of perters in the land, has been on the wane; there is little power left in perting. “Pertogenic” mismanagement is committed while under the influence of PERT. Both words carry hostile connotations, as does the phrase “perting around the bush.”

All of which goes to confirm that the launching of a new acronym is serious marketing business. For historians of management: “PERT” stands for “Program Evaluation and Review Technique.”

“Parkinson’s Law” and “Parkinsonian” ring clinical and convey the air of diagnostic finality. The terms entered the common language and are eminently quotable. “Parkinson’s Law” is already an entry in some newer books of quotations. “PERT” has remained a trade term2.

Professor Parkinson elevated a shrewd observation to the lofty heights of a Law by a deft epigram, the first in modern management. Other pithy gnomic insights followed in quantity: (“Everybody rises to his level of incompetence”), and numerous lesser and ephemeral eponymic “laws.”

“PPBS” is grammatically and idiomatically inert and inflexible. It has remained, for the most part, an enterprise of the government. Its literary tradition, like PERT’s, has followed the classical style of government and corporate reports.

4. Parkinson vs. PERT

“Work expands so as to fill the time available for its completion.” There is a time available or allowed. There is a working span. And there is the difference, the Parkinson Gap, which tends to vanish according to the Law.

Hard core PERT defines and analyzes several types of allowed time for each task and one or more appraisals of its expected duration. A difference between an allowed time and an expected time is one of the arrow’s floats. Some authorities have championed the usage “slack.” FLOAT = SLACK = PARKINSON’S GAP! This is the fundamental link of the two theories.

Most of PERT can be viewed as an analysis of all thinkable and other floats, their relations, economy, and tradeoffs. The critical path is the locus of prime Parkinsonian vulnerability. CF. Appendix.

PERT and Parkinson Address the Same Subject

Parkinson states the universal tendency for work to expand. PERT expands the Law into a marketable technique. The perters vow to counteract or reverse the effects of the Law. But some experienced pertees claim that the perting of a project expands so as to fill all allowed time and budget.

Parkinson is fatalist. It’s not “people expand their work,” the work just expands itself. The pertor, an optimist, offers testimonials and a remedy to the hopeful or desperate manager. Parkinson diagnoses, PERT promises a cure. Both have entered the consulting business.

Parkinson’s Law has remained unchanged in eponym and phrasing. The competitive pressure for product differentiation has resulted in a myriad schediographic label. There is a PERT for every taste and budget.

Detractors of Parkinson disparage his Law as a witticism. No such criticsim has ever been levied at PERT.

PERT is an analytical refinement of Parkinson’s Law. Good PERT husbandry, at least 9.5% of all applications, balances the floats to keep the costs at a minimum. The larger and more complex the network the more there is scope for perting; for a project of a single task PERT and Parkinson’s Law nearly coincide.

From now on PERT and Parkinson’s Law will stay closely coupled. Linked to PERT, the Law will enter the literature on management, administration, and operations research. Perhaps this will revive the ailing PERT industry. Perhaps it will renew public discussions of Parkinsonism in government and business.

Appendix: A Refresher Court in PERT for Senior Management

A perted project is shown as a flow diagram, its pertograph, of activities (jobs) and events. From these time elements one draws conclusions about the whole project, e.g. its duration. Activities are usually drawn as arrows, events as circles. A militant minority champions the opposite usage.

PERT’s Central Dogma: Every project, plan or undertaking is pertable unless it is itself a perting contract or assignment.

Pertographs range from a single arrow to thousands upon thousands of jobs. The diagram below is typical in appearance. Next to each arrow is its expected duration. The activities — arrows — are referred to by letter only, to retain PERT’s universal character; the same diagram serves many scenarios. Pure PERT, in distinction to Applied PERT, can be indulged in without the benefit of an object program to plan, evaluate or review.


Critical Path

This is the project’s longest path, made up of critical arrows usually drawn as double lines. Some young imaginative perters insist on single heavy lines. The critical, or programmed, duration of the project in the diagram is 17 years.

PERT’S most celebrated result, its supreme analytical triumph, was the recognition that the longest path grows longer if its arrows expand (succumb to Parkinson’s Law). This insight was hailed a landmark in modern management theory. Government, industry, and schools of business eagerly adopted PERT. The administrative implications of the critical path were overwhelming. A leading variety of PERT styled itself the Critical Path Method, CPM.

In PERT an arrow’s geometrical length bears no relation to its duration, cost, importance, or need for control. The arrow may be curved. This independence of economic reality was acclaimed an intellectual breakthrough and gave the perters freedom and flexibility undreamt of by older planners.

Size, Budget, Other Techniques

The number of arrows in a pertograph depends mainly on the budget (PERT’s budget, not the program’s). This budget determines the pertee’s entitlement to linear and other programming, to simulation, to stochastic models, etc. PERT mixes with all other methods in any proportion. I combined PERT with decision trees in 1961 (PERTREE).

Pessimistic, Likeliest, Optimistic

Before PERT a manager ignorant of a job’s duration had no scientific recourse. PERT provides a remedy profound in its simplicity. If you are utterly ignorant of the duration of the job X then follow these three steps.

(a) Make or get an optimistic, a likeliest, and a pessimistic appraisal of X’s duration: X1, X2, and X3, (Xj includes a strong Parkinson effect).

(b) Take the average of X1, X2, and X3. Call it Y.

(c) Take the average of Y and X2. This is the PERT estimate of X.

What if on occasion you can’t procure X1, the optimistic estimate? (Or X2, or X3?) PERT won’t let you down. Apply the steps (a), (b), and (c) to estimate X1. You get X11, X12, and X13. X13 is the pessimistic estimate of an optimistic appraisal of the duration of the job X. Etc. Continue until you manage to get the needed estimates or until the project terminates anyhow.

Floats (= Slacks = Parkinson’s Gap)

In the above diagram activity F can be disposed of in 2 weeks but the time allowed is 13 years. The Float of F = 13 years – 2 weeks. Parksinson predicts that this gap will tend to disappear.

The activities B and C require jointly 1 fortnight and 90 minutes but have a joint Parkinsonian Gap (float) of 4 years minus a fortnight minus 90 minutes. The precedence of B means that it’s likely to use up all this slack by itself unless severely supervised. If the project is run backwards it’s C that will while away the joint gap.

In large commercial diagrams the float relations are more complex. There are total, free, and independent floats — to mention the most publicized ones.

Here I have to quit. My Parkinson Gap for this writing has been fully used up.

Reprinted by permission from Interfaces, Vol. 5, No. 1.


* Martin Krakowski received his Ph.D. from Carnegie-Mellon University, has worked as physicist, mathematician, engineer, and management scientist in the oil, electronics, and aerospace industries, was a professor of Operations Research, and has consulted in the U.S. and abroad on management and OR problems.

1 About two months after I sent this article to the Editor this statement was prophetically confirmed. The following is an excerpt from a report by a London correspondent of the Christian Science Monitor, May 30, 1974, page 5.

   “Britons, it seems, can do almost as much work in three days as they do usually in five.

   “That’s what the latest statistics here are showing. The miners’ strike of last winter, which resulted in power shortages and a three-day week for British industry, has proved to be not the economic catastrophe it at first appeared.

   “Preliminary estimates of the gross domestic product for the first quarter of 1974 show a fall of only about 3½ percent compared with the same period of 1973.”

Our Civil Service and private bureaucracy is certainly abreast of the British industry. Almost all the energy used by the bureaucracy is for heating, air-conditioning, and commuting to office; a tiny fraction is utilized for illumination.

2 PERT must have exercised a subtle influence on Vladimir Nabokov when he wrote Pale Fire in 1962. Cf. the diagram in the Appendix.

* “And here time forked,” Vladimir Nabokov, Pale Fire, 1962 (5 years after PERT), Verse 404.

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