Use Case Points (UCP) Guide

Overview

Use Case Points is a software estimation technique that calculates project effort based on use cases and complexity factors.

Step-by-Step Calculation Process

Step 1: Count Unadjusted Use Case Points (UUCP)

Use Case Complexity Classification

Type	Description	Weight
Simple	1-3 transactions	5
Average	4-7 transactions	10
Complex	8+ transactions	15

Actor Complexity Classification

Type	Description	Weight
Simple	System interface (API)	1
Average	Protocol interface (HTTP, database)	2
Complex	Human user interface (GUI)	3

UUCP Calculation

UUCP = (Use Case Points) + (Actor Points)

Step 2: Apply Technical Complexity Factor (TCF)

Technical Factors

Factor	Description	Weight	Rating (0-5)
T1	Distributed system	2
T2	Response time/performance	2
T3	End-user efficiency	1
T4	Complex internal processing	1
T5	Reusable code	1
T6	Easy to install	0.5
T7	Easy to use	0.5
T8	Portable to other platforms	2
T9	Easy to change	1
T10	Concurrent users	1
T11	Security features	1
T12	Access for third parties	1
T13	Training needs	1

TCF Calculation

TFactor = Sum of (Weight × Rating)
TCF = 0.6 + (0.01 × TFactor)

Step 3: Apply Environmental Complexity Factor (ECF)

Environmental Factors

Factor	Description	Weight	Rating (0-5)
E1	Familiar with development process	1.5
E2	Application experience	0.5
E3	Object-oriented experience	1
E4	Lead analyst capability	0.5
E5	Motivation	1
E6	Stable requirements	2
E7	Part-time staff	-1
E8	Difficult programming language	-1

ECF Calculation

EFactor = Sum of (Weight × Rating)
ECF = 1.4 + (-0.03 × EFactor)

Step 4: Calculate Use Case Points

UCP = UUCP × TCF × ECF

Step 5: Convert to Effort

Person-Hours = UCP × Productivity Factor

Productivity Factor Guidelines

Project Type	Hours per UCP
Simple project	20
Average project	28
Complex project	36

Quick Reference Example

Sample Project

• 5 Simple Use Cases (5 × 5 = 25)
• 8 Average Use Cases (8 × 10 = 80)
• 3 Complex Use Cases (3 × 15 = 45)
• 2 Simple Actors (2 × 1 = 2)
• 3 Average Actors (3 × 2 = 6)
• 1 Complex Actor (1 × 3 = 3)

UUCP = 25 + 80 + 45 + 2 + 6 + 3 = 161

Technical Factors (Example)

• T1=3, T2=4, T3=3, T4=2, T5=3, T6=2, T7=3, T8=1, T9=3, T10=4, T11=3, T12=1, T13=2
• TFactor = (2×3)+(2×4)+(1×3)+(1×2)+(1×3)+(0.5×2)+(0.5×3)+(2×1)+(1×3)+(1×4)+(1×3)+(1×1)+(1×2) = 39
• TCF = 0.6 + (0.01 × 39) = 0.99

Environmental Factors (Example)

• E1=4, E2=3, E3=3, E4=3, E5=4, E6=2, E7=1, E8=2
• EFactor = (1.5×4)+(0.5×3)+(1×3)+(0.5×3)+(1×4)+(2×2)+(-1×1)+(-1×2) = 18.5
• ECF = 1.4 + (-0.03 × 18.5) = 0.845

Final Calculation

UCP = 161 × 0.99 × 0.845 = 135 Use Case Points
Effort = 135 × 28 = 3,780 person-hours

Best Practices

Accuracy Tips

• Have experienced analysts classify use cases
• Be consistent in complexity classification
• Review ratings with the development team
• Consider project-specific productivity factors

Common Pitfalls

• Inconsistent use case granularity
• Overly optimistic environmental ratings
• Ignoring project-specific factors
• Not updating estimates as requirements evolve

Validation

• Compare with historical project data
• Cross-check with other estimation methods
• Review complexity ratings regularly
• Adjust productivity factors based on team experience

Integration with Other Methods

Use Case Points + COCOMO

1. Use UCP for initial sizing
2. Apply COCOMO adjustments for technology
3. Combine for more robust estimates

Use Case Points + Planning Poker

1. Use UCP for baseline estimates
2. Validate with team planning poker sessions
3. Reconcile differences through discussion