PLANNING STAGE (TIME) : ESTIMATE ACTIVITY DURATIONS

This is the fifth process of planning time where by amount of time used to complete each activity with estimated resources is estimated. The time can be in form of minutes, hours, days, weeks etc.

The inputs of this process are:

• The activity resource requirements as an output of the previous process where by the allocated resources from each activity can influence the duration of the activity. For example, if you select unskilled persons then there is a need of training them which will lead to longer estimate of time.
• Activity list which mentioned all the activities that need to be provided an estimated time.
• Schedule management plan which explains the method used to estimate time for the activities.
• Project Scope Statement which explains the assumptions and limitations to be considered when estimating the durations.
• Risk register which is a document that list of all the risks during the project implementation and therefore with their consideration, will help to estimate duration. 
• Resource Calendars which explain the availability of the resources during the project period. If the resource performed in full time then the amount of duration used will be different (or less) from the one performing in part time basis.
• Enterprise Environmental Factors which explain if there is a database for estimating the duration.
• Organizational Process Assets which explain the historical information about durations as well as the lessons learnt in the process of estimate activities durations from the previous similar projects.

The process can also be done by using:

• Experts who can provide the recommended durations per activity.
• Analogous estimation whereby the duration can be estimated using the previous similar activities or projects
• Parametric estimation whereby through the relationship between the duration and other project parameters/variables, the duration can be estimated. For example, if a resource is capable to type 100 words in 2 minutes then it will take 20 minutes to type 1000 words.
• Three point estimation where by the duration can be estimated using three points of duration of the activity (most likely (M) based on normal scenario, optimistic (O) based on best scenario and pessimistic (P) based on the worse scenario for the activity). This uses two formulars:
• Triangular distribution as (M + O + P)/3
• Beta distribution as (4M + O + P)/6
• Group decision making where by the project team is engaged to brainstorm together to reach the durations estimate in accurate and become committed with them for execution of works.

The output of this process is called Activity Duration Estimates with possible range of results (+/-) for example, if an activity will take place for 1 week +/- 1 day then it will take in the range of 6 days to 8 days.

References:

PMI (2013). A Guide to the Project Management Book of Knowledge (PMBOK Guide 5^th Ed.) USA, Project Management Institute
https://www.youtube.com/redirect?q=http%3A%2F%2F

Thank you and if you have any questions or suggestions, please don't hesitate to post on the comments below.

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