Program evaluation and review technique: Difference between revisions

Revision as of 23:58, 18 August 2022

Revision as of 14:50, 21 August 2022

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{{Short description|Statistical tool used in project management}}

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{{Redirect|PERT}}

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[[File:Pert chart colored.svg|thumb|309px|PERT network chart for a seven-month project with five [[Milestone (project management)|milestones]] (10 through 50) and six activities (A through F).]]

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Initially PERT stood for ''Program Evaluation Research Task,'' but by 1959 was renamed.<ref name="MRCW 1959"/> It had been made public in 1958 in two publications of the U.S. Department of the Navy, entitled ''Program Evaluation Research Task, Summary Report, Phase 1.''<ref>U.S. Dept. of the Navy. ''[https://web.archive.org/web/20151112203807/http://www.dtic.mil/dtic/tr/fulltext/u2/735902.pdf Program Evaluation Research Task, Summary Report, Phase 1].'' Washington, D.C., Government Printing Office, 1958.</ref> and ''Phase 2.''<ref>U.S. Dept. of the Navy. ''[https://catalog.hathitrust.org/Record/100954569 Program Evaluation Research Task, Summary Report, Phase 2].'' Washington, D.C., Government Printing Office, 1958.</ref> In a 1959 article in ''The American Statistician'' the main [[Willard Fazar]], Head of the Program Evaluation Branch, Special Projects Office, U.S. Navy, gave a detailed description of the main concepts of the PERT. He explained:

{{QuoteBlockquote|Through an electronic computer, the PERT technique processes data representing the major, finite accomplishments (events) essential to achieve end-objectives; the inter-dependence of those events; and [[Estimation (project management)|estimates]] of time and range of time necessary to complete each activity between two successive events. Such time expectations include estimates of "most likely time", "optimistic time", and "pessimistic time" for each activity. The technique is a management control tool that sizes up the outlook for meeting objectives on time; highlights danger signals requiring management decisions; reveals and defines both methodicalness and slack in the flow plan or the network of sequential activities that must be performed to meet objectives; compares current expectations with [[Schedule (project management)|scheduled]] completion dates and computes the probability for meeting scheduled dates; and simulates the effects of options for decision&nbsp;— before decision.<br />The concept of PERT was developed by an operations research team staffed with representatives from the Operations Research Department of [[Booz Allen Hamilton]]; the Evaluation Office of the [[Lockheed Martin Space Systems|Lockheed Missile Systems Division]]; and the Program Evaluation Branch, Special Projects Office, of the Department of the Navy.<ref name="SDFJWM 1959">[[Willard Fazar]] cited in: B. Ralph Stauber, H. M. Douty, Willard Fazar, Richard H. Jordan, William Weinfeld and Allen D. Manvel. "[https://www.jstor.org/stable/2682310 Federal Statistical Activities]." ''The American Statistician'' 13(2): 9-12 (Apr., 1959) , pp. 9-12</ref>}}

[[File:PERT Guide for management use, June 1963.jpg|thumb|upright|''PERT Guide for management use'', June 1963]]

Ten years after the introduction of PERT in 1958 the American [[librarian]] Maribeth Brennan published a selected [[bibliography]] with about 150 publications on PERT and CPM, which had been published between 1958 and 1968. The origin and development was summarized as follows:

{{QuoteBlockquote|PERT originated in 1958 with the ... [[UGM-27 Polaris|Polaris missile]] design and construction scheduling. Since that time, it has been used extensively not only by the [[aerospace industry]] but also in many situations where management desires to achieve an objective or complete a task within a scheduled time and cost expenditure; it came into popularity when the algorithm for calculating a maximum value path was conceived. PERT and CPM may be calculated manually or with a computer, but usually they require major computer support for detailed projects. A number of colleges and universities now offer instructional courses in both.<ref name="MB 1968">Brennan, Maribeth, ''PERT and CPM: a selected bibliography,'' Monticello, Ill., Council of Planning Librarians, 1968. p. 1.</ref>}}

For the subdivision of work units in PERT<ref>Desmond L. Cook (1966), ''Program Evaluation and Review Technique.'' p. 12</ref> another tool was developed: the [[Work Breakdown Structure]]. The Work Breakdown Structure provides "a framework for complete networking, the Work Breakdown Structure was formally introduced as the first item of analysis in carrying out basic PERT/COST."<ref>[[Harold Bright Maynard]] (1967), ''Handbook of Business Administration.'' p. 17</ref>