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Estimating Activity Durations

5 minutes 5 Questions

Estimating activity durations means accurately determining the number of work periods needed to complete individual activities considering all the resources available. Various techniques are used in this process including analogical estimation, parametric estimation, bottom-up estimating, and three-point estimating. Accurate duration estimates are crucial in developing a realistic project schedule. Misestimated activity durations can lead to project delay or cost overrun.

Guide on Estimating Activity Durations

Estimating Activity Durations is a crucial step in Project Time Management within the context of the CAPM (Certified Associate in Project Management) framework. It involves defining the amount of time each task will take to complete, which helps in creating a realistic project schedule.

Importance: This concept is important as it helps prevent delays, budget overruns, and other project risks by developing a well-informed timeline. It aids in coordinating resources, managing stakeholder expectations by providing a clear view of the project's timeline, and contributes to the overall project success.

How it Works: Estimating Activity Durations are usually performed by using techniques such as analogous (past similar activities), parametric (using statistical relationships), and three-point estimates (optimistic, pessimistic, and most likely) based on the Work Breakdown Structure (WBS).

Exam Tips: When answering questions related to this in an exam, remember to:
- Understand the difference between the various estimating techniques.
- Read the question carefully to determine which technique is most applicable.
- Use the given data to solve quantitative problems, like determining which activity duration has the most significant effect on the entire project.
- Explain the importance and benefit of accurate estimation in descriptive type questions.
- Remember the impact of the estimation phase on other project management processes.

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CAPM - Project Time Management Example Questions

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Question 1

You are managing a project in a field in which you have extensive experience. You understand the tasks and their duration required. Which approach would you primarily use?

Correct Answer: Expert Judgement

The best answer is 'Expert Judgement' as you are managing a project in a field where you have extensive experience and understand the tasks and their duration. Expert judgement utilizes the expertise of an individual or a group of individuals to assess the situation, and in this case, that's your role. 'Parametric Estimating' is incorrect because it uses statistical modeling and historical data to calculate an estimate, which is not necessary if you already understand the tasks and their duration. 'Three-point Estimating' is also incorrect because it uses optimistic, pessimistic, and most likely estimates to calculate an overall estimate, which again isn't necessary due to your extensive experience and understanding. 'Analogous Estimating' is incorrect because it uses a similar past project to estimate the duration and cost of the current project. This method is generally less accurate than other methods and is not suitable if you already have a thorough understanding of the tasks.

Question 2

You are overseeing a horticulture project, and you have a detailed record of how long it takes to sow seeds, grow, and harvest certain plants. You have been asked to estimate the duration of these activities for the upcoming harvest season. What would be the most appropriate method to use?

Correct Answer: Parametric Estimating

Parametric Estimating is the most appropriate method because it uses statistical relationship between historical data and other variables to calculate an estimate for activity parameters such as cost, budget, and duration. In this case, the previous records of how long it took to sow seeds, grow, and harvest plants can be used to predict the duration of these activities for the new season. Three-Point Estimating, another estimating method, may not be suitable in this case because it requires uncertainty and risk into account for estimation. Analogous Estimating uses similar past projects to estimate the duration or cost of the current project, but is less accurate than Parametric Estimating. Finally, Monte Carlo Simulation is a technique that uses probability distributions and random sampling to calculate possible outcomes, which may not be necessary in this context given the availability of detailed historical data from the horticulture project.

Question 3

You're managing a project where some activities have fixed durations, while others are variable. Which estimation technique would be most suitable for handling this mix of activity types?

Correct Answer: Three-point estimation

Three-point estimation is the most suitable technique for handling a mix of fixed and variable duration activities in a project.

This method allows for flexibility in estimating by considering three scenarios: optimistic, most likely, and pessimistic estimates. For fixed duration activities, all three estimates might be the same or very close, while for variable activities, there could be a wider range.

Three-point estimation accounts for uncertainty and variability, making it ideal for projects with mixed activity types. It provides a more accurate overall project estimate by considering the potential range of durations for variable activities.

Parametric estimation using standard deviations is less suitable as it relies on historical data and may not account for the unique aspects of each activity.

The Delphi technique with expert judgment can be useful but may be too time-consuming and complex for routine project estimation, especially when some activities have fixed durations.

Bottom-up estimation with contingency reserves is a good approach for detailed estimates but doesn't inherently account for the variability in activity durations as effectively as three-point estimation.

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