Time / Scope Management Michelle Wonacott PROJ 640 Ferris State University
The Process of Estimating Tasks and Project Duration While Building a House
Methods of Estimating Tasks and Project DurationPERT Method • Mathematic formula using optimistic, pessimistic, and most likely time estimates. • Optimistic + 4 x most likely time + pessimistic time ----------------------------------------------------------- 6 • Standard deviation pessimistic – optimistic ----------------------------- then square the answer 6
Benefits and Limitations of PERT Method Benefits: • Provides an expected project completion time • Determines the critical path of a project • Provides the ability to deal with uncertainty in activity completion times Limitations: • Fails to address chronic problems of late completion, over spending, and a need to cut specifications • Fails to take resource availability into account • Pads large amounts of contingency reserve in activities for unexpected delays • Does not account for path convergence and therefore normally tends to underestimate project duration (Agarwal, Borchers, & Crane, 2010)
Methods of Estimating Tasks and Project DurationMonte Carlo Simulation Method • Monte Carlo simulation is a computerized mathematical technique • Simulates various mathematical and scientific situations • A problem solving technique used to approximate the probability of certain outcomes by running multiple trial runs, called simulations, using random variables (Kwak & Ingall, 2007)
Benefits and Limitations of Monte Carlo Simulation Benefits: • Helpful tool when trying to understand and quantify the potential effects of uncertainty of the project • Assists in quantifying and justifying project reserves to deal with the risk events that will occur during the project • Handles path convergence situations Limitations: • High amount of time and resources to complete the simulation activity • Lack of easy-to-use software tools • Can create project duration distributions that are very wide (Kwak & Ingall, 2007)
Methods of Estimating Tasks and Project DurationDelphi Technique • A method used to estimate the likelihood and outcome of future events • A group of experts each individually give estimates and assumptions to a facilitator who reviews the data and issues a summary report • Group members discuss and review the summary report individually, and give updated forecasts to the facilitator, who again reviews the material and issues a second report • Process continues until consensus is reached
Benefits and Limitations of Delphi Technique Benefits: • Provides a scientific methodology that is well suited to issues that require the insights of subject matter experts • Good technique to use when the experts are from various disciplines • Helpful when the issue under investigation does not lend itself to analytical techniques, but instead can benefit from collective subjective judgments Limitations: • The Delphi technique is a qualitative approach, not a quantitative approach • It may also not yield exact repeatable results (Grisham, 2008)
Building a House with the PERT Method • Establish critical path (minimal amount of time it will take to build the house) • Create estimates for the duration of each tasks • Calculate slack time which is the difference between available and estimated (real) time for a task • Slack time is a measure of how much time can be lost without causing major troubles for the project
Building a House with Monte Carlo Simulation • Establish the tasks associated with building the house • Quantify the risk events that will may during the project • Use Monte Carlo simulation software to analyze risks and identify their impact on projects outcomes such as budget and project duration
Building a House with Delphi Technique • Ask for input from experienced contractors and builders • Have the experts reach a consensus on time estimates • Experts will draw upon their prior experience
I have chosen PERT Method for My Project Rationale: • Allows me to set realistic expectations and a more realistic estimate of outcomes • Helps me identify tasks which must be completed on time for the house to be completed on time. Allows me to set priorities. • Identifies which tasks can be delayed without impacting project duration. Allows me to efficiently allocate recourses. • I do not have the resources required for a Monte Carlo simulation • Delphi Technique can be impacted by biases of experts
Involvement of Others in Time Estimation Process • Prior to starting construction estimate durations for each task. Will need to consult with subcontractors for their input. • Prior to starting construction review schedule with suppliers and subcontractors. Confirm material lead times and activity durations. • Through building process frequently review progress schedule with owners. Communication will establish and manage expectations. • Through building process involve inspectors as appropriate. Work to avoid delays due to building code violations.
Resource Quality Will manage quality by: • Setting quality requirements and standards with input from home owners. • Include agreed upon quality requirements in the project plan and use them as basis for performance measurement. • Measure and document results of quality requirement throughout the construction process to determine compliance with agreed upon quality requirements. • In order to maintain quality during work hand-offs the project manager will be present during these transitions to communicate time and quality expectations. Performance measurements will be reviewed with subcontractors.
Application of Safety to Time Estimates • Will utilize buffers to help manage the construction schedule. • Project Buffer – To be inserted at the end of the construction between the last task and the completion date. • Feeding Buffer –To be inserted between the last task on a feeding path and the critical chain. • Resource Buffer - Set alongside critical chain to ensure appropriate people and skills are available to work on tasks as soon as needed. • I will manage scope creep by establishing a vision, understanding priorities, and maintaining the critical path. (Goldratt, 1997)
References • Agarwal, A., Borchers, A., and Crane, M. (2010). Managing multiple projects and departmental performance using buffer burn index. Journal of Academy of Business and Economics, 10(5), 28. Retrieved from http://www.freepatentsonline.com/article/Journal-Academy-Business-Economics • Goldratt, E.M. (1997). Critical Chain. North River Press • Grisham, T. (2009). The Delphi technique: a method for testing complex and multifaceted topics. International Journal of Managing Projects in Business, 2(1), 112-130. Retrieved from citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.153.6892 • Kwak, Y.H. and Ingall, L. (2007). Exploring Monte Carlo simulation applications for project management. Risk Management, 9, 44–57. Retrieved from ttp://home.gwu.edu/~kwak/Monte_Carlo_Kwak_Ingall.pdf