Use Case Points
Slide 1
Use Case Points*
Use Case Points (UCP) is a current technique for
measuring functionality of a software system.
It can be used for each use case or all use cases.
*Apparently also called “use case
function points”, based on analogy to
function point metric.
Slide 2
Use-Case Points
l
A size and effort estimation technique that was
developed around use cases
•
l
Better for OOSAD projects than function points
Requires at a minimum:
•
•
•
The set of essential use cases
The use case diagram
All actors and use cases classified as simple, average,
or complex
Slide 3
Steps of UCP (Use Case Points) Estimation
For each use case:
1. Classify actors, to determine UAW (Unadjusted Actor
weight)
2. Classify use case, to determine UUCW (Unadjusted
Use case Weight)
3. Compute UUCP (Unadjusted Use Case Points)
4. Compute technical and environmental factors
5. Computer the Adjusted Use Case Points
6. Translate into an estimate of human effort
Slide 4
Steps in UCFP Estimation
1. Determine the UAW (Unadjusted Actor weight)
a. Using the Actor Classification Table determine the
classification of each of the actors in the system.
b. Add the values of all the actors to determine the
unadjusted actor weight of the system.
Slide 5
Actor Classification Table
Classification
Simple
Test to recognize classification
Communicate to system through API.
Average
Value/Factor
1
2
Interact with the system through some
protocol (HTTP, FTP, or probably some
user defined protocol), or
Are data stores (Files, RDBMS).
Complex
Interacts through HCI (GUI)
3
Slide 6
Steps in UCFP Estimation
2. Determine number of UUCW (Unadjusted Use case
Weight)
1. Using the Use Case Classification Table, determine
the classification of each use case on the use case
diagram.
2. Add the values of each use case to yield the
unadjusted use case weight.
Slide 7
Use Case Classification Table
Use Case Type
Simple
Average
Complex
Test to recognize classification
1-3 transactions
4-7 transactions
More than 7 transactions
Value/Factor
5
10
15
Slide 8
Steps in UCFP Estimation
3. Determine Total UUCP (Unadjusted Use Case Points)
using the formula below.
Total UUCP = Total UAW + Total UUCW.
Slide 9
Technical Complexity Factors
Factor
Description
Number
Weight
T1
Distributed system
2.0
T2
Response time or throughput performance objectives
1.0
T3
End-user online efficiency
1.0
T4
Complex internal processing
1.0
T5
Reusability of code
1.0
T6
Easy to install
0.5
T7
Ease of use
0.5
T8
Portability
2.0
T9
Ease of change
1.0
Technical Complexity Factor (TCF) = 0.6 + (0.01 * TFactor)
Slide 10
Environmental Factors
Factor
Description
Number
Weight
E1
Familiarity with system development process in use
1.5
E2
Application experience
0.5
E3
Object-oriented experience
1.0
E4
Lead analyst capability
0.5
E5
Motivation
1.0
E6
Requirements stability
2.0
E7
Part time staff
-1.0
E8
Difficulty of programming language
-1.0
Environmental Factor (EF) = 1.4 + (-0.03 * EFactor)
Slide 11
Person-Hours Multiplier
If the sum of (number of Efactors E1 through E6
assigned value < 3) and (number of Efactors E7
and E8 assigned value > 3) ≤ 2
PHM = 20
Else If the sum of (number of Efactors E1 through E6
assigned value < 3) and (number of Efactors E7
and E8 assigned value > 3) = 3 or 4
PHM = 28
Else
Rethink project; it has too high of a risk for failure
Slide 12
Computing Use-Case Points
l
Adjusted Use Case Points (UCP) =
l
UUCP * TCF * ECF
l
Effort in Person Hours =
l
UCP * PHM
Slide 13