1. Alternative Software Size Measures for Cost Estimation
CS 510
Software Management and Economics
Fall 2016
Anandi Hira, USC

2. COCOMO Effort Formulation
# of cost drivers
Effort (person-months) = A (Size)E P EMi
i=1
Where:
A is a constant derived from historical project data (currently A = 2.94 in COCOMOII.2000)
Size is in KSLOC (thousand source lines of code), or converted from function points or object points
E is an exponent for the diseconomy of scale dependent on five additive scale factors according to b = *SSFi, where SFi is a weighting factor for ith scale factor
EMi is the effort multiplier for the ith cost driver. The geometric product results in an overall effort adjustment factor to the nominal effort.
9/19/2016
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3. Software Estimation Accuracy4x 2x
Relative Size Range x
0.5x
SLOC
0.25x
Feasibility
Plans/Rqts.
Design/Architecture
Develop and Test
Need Estimates Here
Phases and Milestones
9/19/2016
©USC-CSSE

4. Function & SNAP Points EIF EI EI EO EO EQ EQ ILF EI EO EQ
EI – External Input
EO – Ext. Output
EQ – Ext. Queries
ILF – Internal Logical File
EIF – External Interface File
DET – Data Element Types
ILF EI EO EQ
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5. Function Points (1/3)
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6. Function Points (2/3) General System Characteristics
General System Characteristics Cntd.
Installation ease
Operational ease
Multiple sites
Facilitate change
Data communications
Distributed data processing
Performance
Heavily used configuration
Transaction rate
Online data entry
End-user efficiency
Online update
Complex processing
Reusability
Value Adjustment Factor (VAF)
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7. Function Points (3/3) New Development Projects Enhancement Projects
Total Project after Enhancements
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8. Subcategory Rating Method Complexity Multiplier Factor
SNAP Points (1/5)
Subcategory
Subcategory Rating Method
Complexity Multiplier Factor
Low
Average
High
Total
Data Operations
Data Entry Validation
# of nesting levels in longest chain
1 – 2
3 – 5
6 +
2 * #DET
3 * #DET
4 * #DET
Logical Operations
# of File Types Referenced
0 – 3
4 – 9
10 +
6 * #DET
10 * #DET
Mathematical Operations
7 * #DET
Internal Data Movement
Data Configuration
# of records configured
1 – 10
11 – 29
30 +
8 * #DET
12 * #DET
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9. Subcategory Rating Method Complexity Multiplier Factor
SNAP Points (2/5)
Subcategory
Subcategory Rating Method
Complexity Multiplier Factor
Low
Average
High
Total
Interface Design
User Interface
# of properties
< 10
10 – 15
16 +
2 * #items
3 * #items
4 * #items
Help Methods
Help Method type and # of items
User Manual
Online/Context
Online + Context
1 * #items
Multiple Input Methods
# DETs and # of additional input methods
DETs
5-15 DETs
16 + DETs
3 * #meth.
4 * #meth.
6 * #meth.
Multiple Output Methods
# DETs and # of additional output methods
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10. SNAP Points (3/5) Subcategory Subcategory Rating Method
Complexity Multiplier Factor
Low
Average
High
Total
Technical Environment
Multiple Platforms
# of platforms 2 3
4 +
Same Family
Diff. Family
Internet Browsers 20 40 10 30 60 80
Database Technology
# of DETs and database operations
1-19 DETs
20-50 DETs
51 + DETs
6 * #oper
9 * #oper
12 * #oper
Batch Processes
# file types referenced
1 – 3
4 – 9
10 +
4 * #DET
6 * #DET
10 * #DET
9/19/2016
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11. Subcategory Rating Method Complexity Multiplier Factor
SNAP Points (4/5)
Subcategory
Subcategory Rating Method
Complexity Multiplier Factor
Low
Average
High
Total
Architecture
Component Based Software
Type of components and # of unique components
In-house
3rd party
N/A
3 * #comp
4 * #comp
Multiple Input / Output Interfaces
# DETs and # of additional interfaces
1 – 5
6 – 19
20 +
3 * # interfaces
4 * # interfaces
6 * # interfaces
9/19/2016
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12. SNAP Points (5/5) New Development Projects Enhancement Projects
Total Project after Enhancements
9/19/2016
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13. Software Estimation Accuracy4x 2x
Relative Size Range x
0.5x
Function & SNAP Points
0.25x
Feasibility
Plans/Rqts.
Design/Architecture
Develop and Test
Need Estimates Here
Phases and Milestones
9/19/2016
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14. Use Case - Written Brief Description
Bank Customer uses the ATM to withdraw money.
Actors
Bank Customer; Bank
Preconditions
There is an active network connection to the bank.
The ATM has cash available
Basic Flow
Bank Customer inserts ATM/Debit card
Validate user
ATM displays and prompts for account
Bank Customer selects account
ATM displays alternatives
Bank Customer selects withdraw option
ATM prompts for amount
Bank Customer enters an amount
ATM sends info to Bank as transaction
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15. Use Case – Written Cntd. Basic Flow Money is dispensed
ATM/Debit card is returned
Receipt is printed
Alternative Flows
2a. If user is not validated, then return error
8a. If Bank Customer enters an amount that cannot be created with the type of cash in the ATM machine, display a message that amount must be in multiple of 20. Ask Bank Customer to re-enter amount.
8b. If Bank Customer enters an amount that exceeds the withdrawal limit, display warning message and ask Bank Customer to re-enter amount.
8c. If Bank Customer enters an amount that exceeds the amount available in account, return warning message and ask Customer to re-enter. …
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16. Use Case - Diagram Withdraw Cash Transfer Funds Deposit Funds
Bank Customer
Deposit Funds
Bank
Refill Machine
Maintenance Person
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17. Use Case Points (1/4) Use Case Complexity # of Transactions Weight
Simple
3 or fewer 5
Average
4 to 7 10
Complex
More than 7 15
Actor Complexity
Actor Type
Weight
Simple
System through API 1
Average
System through protocol
Person through text-based interface 2
Complex
Person through GUI 3
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18. Use Case Points (2/4) Tech-nical Factor Description Weight T1
Distributed System 2 T2
Performance Objectives T3
End-user Efficiency 1 T4
Complex Processing T5
Reusable Code T6
Easy to Install
0.5 T7
Easy to Use
Tech-nical Factor
Description
Weight T8
Portable 2 T9
Easy to Change 1
T10
Concurrent Use
T11
Security
T12
Access for 3rd Parties
T13
Training Needs
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19. Use Case Points (3/4) Environ-mental Factor Description Weight E1
Familiar with Development Process
1.5 E2
Application Experience
0.5 E3
Object-Oriented Experience 1 E4
Lead Analyst Capability E5
Motivation E6
Stable Requirements 2 E7
Part-time Staff -1 E8
Difficult Programming Language
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20. Use Case Points (4/4) Unadjusted Use Case Points Use Case Complexity
+ Actor Complexity
Technical Complexity Factor (TCF)
Environment Complexity Factor (EF)
Unadj. Use Case Points x TCF x EF
Use Case Points
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21. Software Estimation Accuracy4x 2x
Relative Size Range x
0.5x
Use Case Points
0.25x
Feasibility
Plans/Rqts.
Design/Architecture
Develop and Test
Need Estimates Here
Phases and Milestones
9/19/2016
©USC-CSSE

22. Agile Methodology
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23. User Stories Structure Example
As a <Type of User>, I want <To Perform Some Task>, So that <I can achieve some Goal / Benefit / Value>
As a Customer, I want to withdraw cash from an ATM, So that I don’t have to wait in line at the Bank
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24. Story Points Planning Poker Development Team Planning Poker Cards
Fibonacci Series (1, 2, 3, 5, 8, 13, 21, …)
Estimate Size (not effort)
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25. Software Estimation Accuracy4x 2x
Relative Size Range x
0.5x
Story Points
0.25x
Feasibility
Plans/Rqts.
Design/Architecture
Develop and Test
Need Estimates Here
Phases and Milestones
9/19/2016
©USC-CSSE

26. Software Estimation Accuracy4x 2x
Relative Size Range x
Use Case Points
0.5x
Function & SNAP Points
Story Points
SLOC
0.25x
Feasibility
Plans/Rqts.
Design/Architecture
Develop and Test
Need Estimates Here
Phases and Milestones
9/19/2016
©USC-CSSE