Tools for Project Resources Estimation
- Rough Order of Magnitude (ROM) Estimation
- Analogous Estimation of resources
- Parametric Estimation of project resources
- Three-Point Estimation:
- Triangular Estimation (Simple Average)
- Beta Estimation (Weighted Average)
Points to Note:
- Each method has strengths and weaknesses
- Estimation should be based on several methods, which should deliver the same results approximately
ROM Estimation
- Very approximate, Ball Park estimate, not based on any detailed data
- Accuracy of ±35% (−25% to +75% by PMBOK-6)
- Example: Initial Estimate for Peshawar metro (Rs 49 billion); current estimate Rs 68 billion (38% increase)
Analogous Estimation
- Estimation based on historical data from a similar Activity of Project, such as duration, budget, size, weight, complexity, etc., suitably corrected for changes since the previous activity or Project
- Example: The new Project is estimated to cost Rs 50 million and take two years to complete based on data from the previous two Projects which were identical to the new one
Parametric Estimation
Estimation based on Industrial Rates or Standards
Examples
- Construction cost of a building of 10,000 square-ft covered area estimated at Rs 28 million, based on A1 Construction Rate of Rs 2,800 per square ft
- 880 bags of cement required to pour 5,000 cu-ft of concrete @ 17.6 bags per 100 cu ft
Three-Point Estimation
- Estimation based on Best-Case (O), Worst-Case (P) and Most Likely (M) scenarios, taking either their Mean, or Weighted Mean [O=Optimistic, P=Pessimistic, M=Most Likely]
- Example: Depending on rains –normal, prolonged, or brief -a Construction Project will take 68, 80 or 60 weeks to complete. What is the planning estimate?
Three-Point (Triangular) Estimation
- Equal Weightage given to O, M, P
- Three-Point (Triangular) Estimate
= (60+68+80)/3 = 70 weeks
Three-Point (Beta) Estimation also known as PERT*
- Equal Weightage given to O & P, but 4 times as much to M
- Three-Point (Beta) Estimate
= (60+4×68+80)/6 = 69 weeks
(*Program Evaluation & Review Technique)
Collecting Requirements
Collecting Requirements = Requirements Traceability Matrix + Requirements Documentation
Requirements Documentation comprises:
- Business Requirements (issues, opportunities, reasons)
- Stakeholder Requirements
- HRD Requirements (training etc. to go from “as-is” to “to-be” status)
Requirements Traceability Matrix
(RTM) Links Product Requirements from their Origins to:
- The Project Objectives
- Deliverables that satisfy them
- Validation parameters (Test Cases)
