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6.4 Estimate Activity Durations: - Coggle Diagram
6.4 Estimate Activity Durations:
What is it?
Estimate the duration needed to complete each activity with estimated resources.
Why?
To avoid underestimating the amount of time each activity will take to complete.
To estimate without correlating
resource
availability.
Project Resources:
Can include material, people, equipment, or anything else required for completing a project activity, typically excluding labor.
When?
Throughout the project.
How?
Consider assumptions and constraints (e.g., resource quality, staff motivation, deadlines).
Estimate activity duration using appropriate techniques.
Determine uncertainty and estimate contingent reserve.
Re-evaluate and adjust to optimize completion.
Finalize and document the duration estimates.
Estimating Techniques:
Analogous Estimating
Uses information from a similar previous project (duration, budget, size, complexity).
Generally less costly and time-consuming, but less accurate.
More accurate if the previous project is similar in nature.
Also known as top-down estimating and expert judgment based on historical data.
Parametric Estimating
Uses a statistical relationship between historical data and other variables.
More accurate than analogous estimating.
Example: A resource takes 20hrs per module, so 50 modules would take 1000hrs.
Estimation is done by multiplying the work quantity by labor hours per unit of work.
Bottom-up Estimating
Decomposes activities into more detail when estimating with confidence is difficult.
Summing up these estimates results in the overall activity estimate.
The most accurate method.
Three-point Estimating (PERT)
Used when historical data or judgmental data is insufficient.
Average of optimistic, most likely, and pessimistic estimates improves accuracy.
Pessimistic estimate (P): Worst-case scenario.
Most likely estimate (M): Realistic estimate.
Optimistic estimate (O): Best-case scenario.
Analysis:
Reserve Analysis
Contingent Reserve time (also called time reserves) may be added as a percentage or a set number of work periods.
Contingency reserve should be clearly identified and documented for future analysis.
Alternatives Analysis
Used to determine the best method to complete an activity, considering various resource allocations.
Output of Process:
Activity Duration Estimates
Quantitative assessments of the time needed to complete an activity, phase, or project.
Do not include lags, but may indicate a range (e.g., 15 days ± 2 days).
Basis of Estimates
Additional details supporting the duration estimate.