Step-5] Estimate Activity Duration

Pre-requisite for this step:  Below deliverables should be available for this step
1.       Work Packages identified
2.       Activity list that describe each of the activities are defined
3.       Activity sequencing that describe how each of the activities are related to each other are clear
4.       Quantity, Type and category of the resources required to complete the activity is clear

Objective of this step: Estimate the number of work periods needed to complete individual activities with estimated resources.  That is we will detail the amount of time each activity will take to complete
1. Outputs:

Activity Duration Estimates - Likely work periods that are required to complete the activity. These do not include any lags/leads.  For example, the activity estimate can be:
2 weeks +/- 2 days:à Activity will at least take 8 working days and the maximum it takes 12 working days (assuming a five day work sheet)

Project Document Updates - Activity Attributes - Assumptions made in developing the activity duration estimates, such as skill levels and avaialability and basis of estimate durations

2. Tools and Techniques:
A. Expert Judgement – Guided by historical information, Expert Judgement can provide duration estimate information from prior similar projects.
B. Analogous Estimating - Analogous in English Language means Similar, Equivalent, and Comparable. Thus,  we take similar projects executed in the past and adjust current differential requirement sizing through expert Judgement – Similarity can be complexity, weight, size, budget and duration - Thus it is Top Down Approach based on historical similar previous project experience - - Adjusted for current project complexity. Less Accurate -Less Time taking - best suited for ball park estimates where less info is available. Most reliable when previous projects are similar in fact not just in appearance. When limited information is available, Analogous estimating is best adopted approach. It is less costly and less time consuming and less accurate.  It is more reliable only when the previous projects we take are similar in the fact not just in the appearance.
C.  Parametric Estimation: An algorithmic model is built based on parameters and historical info. An algorithm is used to calculate cost, duration based on historical data and project parameters. Example, Per Square Foot cost in construction, Function Points, use case points.  Lines of Code etc. Once parameter is arrived, then it is aggregated to Duration and Cost based on historical info available.  It can produce higher levels of accuracy depending on the underlying model accuracy. This can be applied either to total project or particular phases of project.
D. Three Point Estimation:  Considers Estimation uncertainty and involved risks. It can be done in two ways
Triangular Estimation
Beta/PERT Estimation
Duration = {Most Likely + Optimistic (best case scenario)+ Pessimistic [Worst case Scenario]}/3
Duration =  (Most Likely + 4*Optimistic + Pessimistic)/6
Equal probability for Most likely, Optimistic and Pessimistic estimates exists (i.e. 33.33%)
Un Equal Probability for Most likely, Optimistic and Pessimistic estimates exists.  Most likely is probable by 67% and rest of the estimates are probable by 16.5%

E. Group Decision making techniques: Brainstorming - Delphi techniques for engaging team members to improve estimate accuracy and commitment to the emerging estimates.
F. Reserve Analysis:

Contingency Reserves are approved for Known and Risks (i.e. Known unknowns) where risk response strategy is approved by steering committee - These efforts are included as part of schedule baseline

Schedule Baseline Effort = Activity Efforts + Contingency reserve efforts
Management Reserve - For Unknown Unknowns (i.e. For Unknown Risks) (eg. Calamity, Earth Quake) - Not included as part of schedule baseline. Management reserve efforts are taken trough Change control procedure

Project Efforts = Schedule Baseline Efforts + Manager Reserve Efforts

3. Inputs:
Schedule Management Plan - Activity List - Activity Attributes- Activity Resource Requirements - Resource Calendars - Project Scope statements - Risk Register [List of Risks, along with results of risk analysis, risk response planning, Updates to risk register] - Resource Break Down Structure - Enterprise Environmental Factors [Productivity Metrics, Duration Estimation Data, Published commercial info, Location of team members] - Org Process Assets [Historical info - Lessons Learnt- Scheduling Methodology- Project Calendars]

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