UCPEstimation May 10th
-
Upload
upasanakanwal -
Category
Documents
-
view
10 -
download
0
description
Transcript of UCPEstimation May 10th
Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Size Estimation using UCP
2Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Objectives
•To describe relevance of Size Estimation•To understand the concepts and mechanics of
Use Case Point (UCP) Estimation
3Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Assumptions
•Familiar with Estimation concepts•Familiar with WBS Estimation and other
techniques•Familiar with Use Case Modeling concepts and
terminology
4Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Agenda
•Estimation - Introduction•Relevance of Size Estimation•Why Use Case Point (UCP)Estimation?•Use Case Point Estimation framework task
workflow
5Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Estimation - Introduction
• What are Estimates?• Bottom Up (grassroots or engineering) Estimates
• WBS based estimates.
• Top Down Estimates• Not WBS based. (Function Point, Object Point, Use Case Point,
COCOMO)
• Best Practices for Estimation• Combine estimates from different experts and estimation
strategies• Estimate top-down and bottom-up independently• Justify and criticize estimates
• Use method based estimates to improve expert estimates
6Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Relevance of Size Estimation
•Why do we need Size Estimates?• To support planning, budgeting and monitoring
activities• To verify project viability• To elaborate technical and commercial proposals• To get early and precise effort estimates
•SEI-CMMI model mandates use of size estimation as basis for Effort, Schedule and Cost Estimation.
7Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
What is UCP?
Use Case Point (UCP) Size Estimation•A method for estimating software development
effort based on use cases•The Use Case Point (UCP) estimation method
was introduced by Gustav Karner in 1993•It is inspired by Function Point Method•It defines the functional scope of the system to
be developed. The functional scope is the basis for top down estimation.
8Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
How is it Calculated?
• Classify Actors• Classify Use Cases• Define Technical Complexity Factors• Define Environmental Factors• Calculate Use Case Points (UCPs)
9Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Estimation Framework Task flow
Classify Actors Compute Unadjusted Actor Weight (UAW)
Classify Use CasesCompute Unadjusted
Use Case Weight (UUCW) based on Transactions or
Analysis ClassesCompute Unadjusted
Use Case Points
Compute Environment Factor (Efactor)
Arrive at Use Case Points (UCPs)
Arrive at Productivity Index Arrive at Effort Estimate
Compute Technical Complexity Factor
(Tfactor)
10Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Level Of Effort
•Effort Estimation = Software Size * Productivity Index
UCP * Productivity Index•Size is independent of platform•Productivity Index is dependent on platform
11Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Few points to note
•Issues•No formal standard for use case writing•Dependent on well written, well structured
use cases•Technical and the Environmental Factors
have a high impact on the estimate•Combine similar actors in to one super actor•Ignore include and exclude use cases
12Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Advantages
•UCP is easy to Use•UCP method is User-Friendly
• Basis for object-oriented implementation• Can be measured very early in the lifecycle
•Use Cases makes more sense to users• User centered (more robust, what rather than how)
•Does not call for additional analysis
13Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Advantages …
• Use case modeling is increasingly being used as a method of choice to describe requirements and as a basis for design, development, testing, deployment, configuration management and maintenance.
• UCP based estimates are found to be close to actuals when estimation is performed by experienced people
• UCP may support expert knowledge when a use case model for the project is available
14Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Summary
•Relevance of Size Estimation•Why Use Case Point (UCP) Size Estimation?•UCP framework task flow•Advantages of UCP
15Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Thank You
16Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Actors Classification
Simple Actor
Average Actor
Complex Actor
Another System with a defined APIWeighting Factor: 1
Another System interacting through a ProtocolWeighting Factor: 2
Person interacting through GUIOr a Web-Page
Weighting Factor: 3
17Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Unadjusted Actor Weight Computation
Actor Type
Description Factor
Number of Actors
Actor Weight
Simple Another System with defined API
1
Average Another system interacting through a Protocol such as TCP/IP
2
Complex
A person interacting through a GUI or a web page
3
Unadjusted Actor Weight (UAW)
18Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Use Cases Classification
Simple Use Case
Average Use Case
Complex Use Case
Transaction is an action (step) in the scenario
<= 3 TransactionsWeighting Factor: 5
4 to 7 TransactionsWeighting Factor: 10
>= 8 TransactionsWeighting Factor: 15
19Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Use Cases Classification …
Simple Use Case
Average Use Case
Complex Use Case
<= 5 ClassesWeighting Factor: 5
5 to 10 ClassesWeighting Factor: 10
>= 10 ClassesWeighting Factor: 15
20Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Unadjusted Use Case Weight Computation
Use Case Type
Description Factor
Number of Use Cases
Use Case Weight
Simple <= 3 Transactions / Key scenarios or <= 5 Analysis Classes
5
Average 4 to 7 Transactions / Key scenarios or 6 to 10 Analysis Classes
10
Complex > 7 Transactions / Key scenarios or > 10 Analysis Classes
15
Unadjusted Use Case Weight (UUCW)
21Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
UCP Calculations
•Unadjusted Use Case Points (UUCP)
= UAW + UUCW
22Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Technical Complexity Factor (TCF)Factor
Description Weight
Assigned Value (0 to 5)
Calculated factor
T1 Distributed System 2.0T2 Response time or throughput
performance objectives1.0
T3 End user efficiency 1.0T4 Complex internal processing 1.0T5 Code must be reusable 1.0T6 Easy to install .5T7 Easy to use .5T8 Portable 2.0T9 Easy to change 1.0
T10 Concurrent 1.0T11 Includes special security
objectives1.0
T12 Provides direct access for third parties
1.0
T13 Special user training facilities are required
1.0
Total Technical Factor (Tfactor)
23Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Environment Factor (EF)Factor
Description Weight
Assigned Value (0 to 5)
Calculated factor
F1 Familiar with the project model that is used
1.5
F2 Application experience .5
F3 Object-oriented experience 1.0
F4 Lead analyst capability .5
F5 Motivation 1.0
F6 Stable requirements 2.0
F7 Part-time staff -1.0
F8 Difficult programming language -1.0
Total Environment Factor (Efactor)
24Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
UCP Calculations
•Technical Complexity Factor (TCF) = 0.6 + (0.01 x Tfactor)
•Environment Factor (EF)= 1.4 + (-0.03 x Efactor)
•Adjusted Use Case Points (UCP)= UUCP x TCF x EF
25Copyright ©2004 Virtusa Corporation | CONFIDENTIAL
Productivity Index
•Productivity Index (PI) for J2EE applications= 20 to 30 Hrs / UCP
•Karner Proposed 20 Staff Hours per UCP•Estimated Effort = UCP x PI
26Copyright ©2004 Virtusa Corporation | CONFIDENTIALUSA India Sri Lanka
Corporate Headquarters2000 West Park Drive
Westborough, MA 01581 USA
508.389.7300www.virtusa.com