Techniques for Estimating Task Duration in Project Management
As part of planning a project, tasks are assigned to project team members. Durations for task completion are also specified. Task duration estimation is necessary since it helps in cost and resource estimation. Iranmanesh and Mokhtari (2008), further affirmed the importance of project duration estimation by saying that, estimation of time and cost to complete work in a project and follow up them during implementation are major contributors to success or failure of a project, and hence very salient for the Project Manager. According to Hill, Thomas and Allen (2000), developing accurate estimates of overall project duration and its separate activities, is critical in monitoring and controlling of project. Task estimation is considered as a random variable. Therefore estimating duration of task is an informed or educated guess based on past experience of similar tasks. For complex project, it is very difficult to estimate task duration. Therefore, to make a meaningful task duration estimates, some basic information is essential. This information includes scope document, work breakdown structure (WBS), associated risk, task list, task details, and task dependencies. Schedule risks and the critical path are also essential.
Hill, Thomas and Allen (2000) asserted that, the effectiveness of project management techniques depend heavily on the accuracy of the task duration estimates. Thomas (2010) cited in Wysocki (2009) identified six techniques of task duration estimation. These are as followed: similarity to other activities, historical data, expert advice, Delphi technique, Wide-band Delphi technique, and Three-point technique. He identified the Delphi technique and the Three point techniques as the suitable techniques widely use by project management practitioners. My intention is to discuss these methods and how they were applied in my own experience in managing projects.
Historical data: This
References: 1). Seyed Hossein Iranmanesh, and Zahra Mokhtari (2008) Application of Data Mining Tools to Predicate Completion Time of a Project, Academy of Science: Engineering & Technology, August Vol. 44, p234-239. 2). Hill J. Thomas C. L. and Allen E. D. Experts ' estimates of task durations in software development projects, International Journal of Project Management 18 (2000) 13-21 3). Wysocki, R.K. (2009) Effective Project Management: traditional, agile, extreme. 5th ed. Indianapolis: Wiley Publishing. (pp. 148-152). 4). Goodman P., A. (1999). Application of cost estimation techniques: industrial perspective. Information and Software Technology;34:379-82. 5). Shepperd M. (1995). Foundations of software measurement.Englewood Cliffs, New Jersey: Prentice-Hall. 6). Kerzner H. (1995) Project Management: a systems approach to planning scheduling and control. New York: van Nostrand Reinhold 7). Franchina T. (2010). The Six Method of Estimating Task Duration. (Accessed: http://projectmanagementforum.wordpress.com/about/) 21/03/2012