FPA Mark I (AIT)

8/3/2019 FPA Mark I (AIT)

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Estimation TechniquesFPA - Mark I (Albrechts Method)


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Pre-requisites

Trainees should

Know Need forEstimation

Know Estimation Process & Flow

Be aware of Estimation Techniques (Overview)


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Objectives

The participants will be able to

Estimate the size of software requirements using FPA for Development projects

Enhancement projects

Apply Quick FPA


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Contents

FPA- Albrechts Method (Mark I) for development projects

Identify types of function point & transaction point counts

Calculate Unadjusted Function Points

Degree of Influence & Value Adjustment Factor

Calculate Function Point Index

Compute efforts & map to the schedule

Apply FPA for enhancement projects

Quick FPA

Useful Sites


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FPA - An Overview

Albrecht [1] states that:

The purpose...is to provide each Application Development and

Maintenance site a consistent way to measure, portray anddemonstrate the productivity of their AD/M activities

FPA aims to provide a consistent measure of system size that: is independent of the development technology

is simple to apply

can be estimated (reasonably well) from the requirements specification

is meaningful to the end user

Where not to use Systems Programming

Maintenance Projects

Non Functional Testing Performance

Reliability

Security

Scalability


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FPA - Albrechts Method

By Allan Albrecht of IBM in 1979

What are function points A measurement of information processing content of a

systems delivered function

Function decomposition technique

Break application into smaller components


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FPA - Albrechts Method Contd

Can be counted early in lifecycle

Language/Platform/Technology independence

Consistency within organization


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Steps to Compute FP Index

Determine the Type of Count

Identify Application Boundary

Identify Data Function Points

Count Transaction Function Points

Compute Unadjusted function points (UFP)


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Steps to Compute FP Index Contd .

Compute Degree of influence (DI)

Multiple sites

Installation/operational ease

Distributed processing

Data communication

Performance

OLTP requirements etc.

Compute Technical Complexity Adjustment

Compute Function Point Index


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Types of Count

Development Projects

User functionality in the project on first installation

Results in an application base

Application or Baseline FP (Existing Projects)

Current functions of the application

Updated every time after enhancements

Enhancement Projects

Size of renovation / modification of the project

Enhancement of existing project

Equal to sum of areas of New FP, Changed FP andRemoved FP


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Case Study

About a software company

Develop an application for warehouse management


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Case Study-Entities

Customers

Name

Address

Amount Due

Items

Description

Pallets

Storage Date

Storage Place

Location

Space


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Case Study-Entity-Relationship

CustomersName

AddressAmount Due

ItemsDescriptionPallets

Storage DateOwnerStorage Place

Storage PlaceLocationSpace


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Case Study - Transactions

Add customer

Change customer data

Delete customer Receive payment

Deposit item

Retrieve item

Add place

Change place data Delete place

Print customer item list

Print bill

Print stored items list

Query customers Query customer's items

Query places

Query stored items


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Case study Sample UI


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Application Boundaries

The border between the application and external applications ormanual user domains

Determine the scope of work to be automated (functionality)

Boundary is not a physical form

Use a boundary to

Identify interfaces with other systems

Identify interfaces with users

Identify data stores and data entities

The boundary for an internet application is defined in a similar wayfor traditional applications


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Case Study-Identify Application Boundary


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Identify Data Function Points

Internal Logical files (ILF)

External Interface files (EIF)

Two inputs required

RET Record Element Type

User recognizable subgroup of data elements with the ILF / EIF

DET Data Element Type (DET)

Unique attribute or a field

Contains information that is dynamic and not static


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Terminologies

RET (Record Element Type)

DET (Data Element Type)

FTR (File Type Referenced)


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Data Element Type (DET)Counting Rules

Count a DET for each unique user recognizable, non-repeating field maintained in the ILF or retrieved from the

EIF through the execution of an elementary process

When two applications maintain and / or reference the sameILF / EIF, but each maintains/references separate DETs,count only the DETs being used by each application to size

the ILF / EIF

Count each DET for each piece of data required by the userestablish relationship with another ILF / EIF


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Record Element Type Counting Rules

Count a RET for each optional or mandatory subgroup of theILF / EIF

If there are not subgroups, count the ILF or EIF as a RET

Entity RET DET

Customer 1 (CustomerRecord)

3 (Name, Address, Amount)

Item 1 (Item Record) 5 (Description, Pallets,Storage Date, Owner,

Storage Place)

Place 1 (Place Record) 2 (Location, Space)


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Internal Logical Files (ILF)

Logically related data within the application boundary that ismaintained and used by the application most frequently.

Examples: Application data like Customer Master, Supplier Master,Item/Part Master, Message Table

A user identifiable group of logically related data that residesentirely within the applications boundary and is maintained throughexternal inputs.


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Internal Logical Files (ILF) Contd .

Rules

Group of Data or control information is logical, user identifiable,and fulfils specific user requirements

Data is maintained within the application boundary

Data is modified via an elementary process (One or more EIs)

Has not been counted as an EIF for the application

Each ILF is counted only once in the application

Do not count files introduced for technical implementation likeindex, work files, checkpoint files

Do not count system files

Classify the ILFs as Simple, Average, Complex

Based on no. of data elements

No. of data groups involved


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Internal Logical Files (ILF)- Case Study

ILF RET DET Weight

Customer 1 (CustomerRecord)

3 (Name, Address, Amount ) 10

Item 1 (Item Record) 5 (Description, Pallets,Storage Date, Owner,

Storage Place)

10

Place 1 (Place Record) 2 (Location, Space) 10

Total 30

Weighatges for ILFs :-

Simple: 7

Average: 10

Complex: 15


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External Interfaces (EIF)

Logically related data outside the application boundary, used bythe application

Examples

Table maintained by other application but used by the application

A user identifiable group of logically related data that is used forreference purposes only. The data resides entirely outside theapplication and is maintained by another application. This means anEIF counted for an application must be an ILF in anotherapplication.


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External Interfaces (EIF) Contd

Rules

Group of data or Control information is a logical, useridentifiable, and fulfils specific user requirements

Group of data is referenced by, and external to, the applicationbeing counted

Group of data has not been counted as an ILF by the application

Each EIF is counted only once in the application

EIFs are not maintained by the application

Do not double count with internal logical files

Classify the EIFs as Simple, Average, Complex

Based on no. of data elements No. of data groups involved


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External Interfaces (EIF) Case Study

EIF = 0


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Things to Remember

Stand alone systems will not have an EIF

Same file cannot be an ILF and EIF in the same application

Same file can be EIF for multiple applications

Same file can be ILF for multiple applications, if all theseapplications are updating the file


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Transaction Function Points

Transactions are the data that do the processing in the application

Transaction Function Points are contributed by External Inputs (EI)

External Outputs (EO)

External Inquiries (EQ)

Two inputs required FTR File Type Referenced

DET Data Element Type


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FTR File Type Referenced

FTR

File Type Referenced by a transaction

Must also be an ILF or EIF

FTR Counting Rules

Count a FTR for each ILF maintained

Count only one FTR for each ILF maintained and read in

the transaction


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External Inputs to the application (EI)

Related group of user data or control information that enters theboundary of the application. Ex: Maintenance screen(Add/Modify/Delete/View), Transactions input from various users,Control Inputs

May maintain one or more Internal Logical Files (ILFs)

Is an elementary process in which the data crosses the boundaryfrom outside to inside. This data may come from a data inputscreen, electronically or another application. The data can be eithercontrol information or business information. If the data is business

information, it is used to maintain one or more internal logical files.If the data is control information, it does not have to updateinternal logical file.

External Inputs (EI) Contd


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External Inputs (EI) Contd

Related group of user data or control information that enters theboundary of the application. Ex: Maintenance screen(Add/Modify/Delete/View), Transactions input from various users,

Control Inputs

May maintain one or more Internal Logical Files (ILFs)

EI Id ifi i R l


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EI Identification Rules

Each unique class of batch transaction is counted as 1 inputtype, even if many different classes come inside one filestructure. These could be different record formats.

Add, modify and Delete will be 3 inputs

Dont count multiple occurrences of the same unique logical

data item more than once, eg. Repeating rows on a screen

Count data items not displayed but created as a result ofinput (error messages, confirmation messages, calculatedfields etc)

Dont count static information such as constants, screenprompts etc

E t l I t (EI) C St d


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External Inputs (EI) Case Study

EI DET FTR (File typeReferenced)

Weight

Add customer Name, Address, Amount due, Errormessage

Customer 3

Change customerdata

Name, Address, Amount due, Owner,Error message

Customer,Item

4

Delete customer Name, Address, Amount due, Errormessage

Customer,Item

3

Receive payment Amount due, Error message Customer 3

Deposit item Description, Pallets, Value, Storage date,Owner, Storage place, Error message

Customer, Item, Place 6

Retrieve item Amount due, Description, Pallets, Value,Storage date, Owner, Storage place,Error message

Customer,Item

4

Add place Location, Space, Error message Place 3

Change place data Location, Space, Storage place, Errormessage

Place, Item 3

Delete place Location, Space, Error message Place, Item 3

Total 32

E t l O t t t th li ti (EO)


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External Outputs to the application (EO)

Related group of user data or control information that leavesthe boundary of the application. Ex: Customer Invoice (Pre-formatted o/p), Reports to printer or other media, O/P to

other applications. May be generated using Internal Logical Files (ILFs)

An elementary process in which derived data passes acrossthe boundary from inside to outside. The data createsreports or output files sent to other applications. Thesereports or files are created from one or more internal logicalfiles and external interface file.

E t l O t t t th li ti (EO)


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External Outputs to the application (EO)

Rules The processing logic must contain at least one mathematical formula or

calculation or create derived data

It uses at least one ILF or EIF

Each unique batch transaction type being sent to another application iscounted as 1 type

Each medium output is counted as 1 EO

Multiple occurrences of the same unique logical data item are not becounted more than once (repeating rows)

Static information or system generated information like reportheadings, data / time stamps, automatic page numbers are not counted

Treat each output as separate if format or processing logic is different

Do not count enquiry outputs

Classify the EOs as Simple, Average, Complex Based on no. of data elements


Cl ifi ti f M 1


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Classification of Messages 1

Error messages

Employee not found

Pin code is missing

Confirmation messages

Wait. Search is on

Neither of these types of messages is treated as an EO

They are treated as data elements (DET) for the appropriatetransaction

Cl ifi ti f M 2


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Classification of Messages 2

Notification Messages

Processing completed successfully

insufficient funds in account

Notification message is a business type message

It is the basis of processing and a conclusion being drawn

A notification message is treated as an EO

E t l O t t C St d


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External Outputs- Case Study

EO DET FTR Weight

Printcustomeritem list

Name, Description,Value, Storage date,Total items, Total value

Customer,Item

7

Print bill Name, Address, Amountdue, Total items

Customer,Item

7

Print storeditems list

Description, Pallets,Storage place, Totalitems

Item 5

Total 19



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Related group of user data or control information that enters theboundary of the application and generates an output. Ex: Userrequest to display specific set of data, Help request and answer.

May be generated using Internal Logical Files (ILFs)

Is an elementary process with both input and output componentsthat result in data retrieval from one or more internal logical files

and external interface files. This information is sent outside theapplication boundary. The input process does not update anyinternal logical files and output side does not contain derived data.



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Rules

An EQ is made up of input and output

It requests immediate retrieval of data and does not result in

any updates of ILF

EQ may use one or more ILF / EIF

An EQ can not have calculated or derived data

No ILF is maintained in the process

Treat each enquiry as separate if format or processing logic is

different

Do not double count with Inputs/Outputs

Classify the EQs as Simple, Average, Complex

Based on no. of data elements


External Inquiries (EQ) Case Study


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External Inquiries (EQ) Case Study

EQ DET FTR Weight

Querycustomers

I/P: Name, error messageO/P: Name, address, Amountdue

Customer 3

Querycustomer'sitems

I/P: Name, error messageO/P: Name, Description,Pallets, Value, Storage date

Customer,Item

6

Queryplaces

I/P: Location, Error MessageO/P: Location, Space

Place 3

Query

storeditems

I/P: Location, Error Message

O/P: Location, Space,Description, Pallets

Place,

Item

6

Total 18

Compute Unadjusted Function Points (UFP)


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Compute Unadjusted Function Points (UFP)

Compute the unadjusted function points using followingweights

Item Number Points Total

External Inputs x 3

x 4

x 6

External Outputs x 4

x 5

x 7

External Inquiries x 3

x 4

x 6

Internal Logical Files x 7

x 10

x 15

External Interfaces x 5

x 7x 10

Compute UFP Case Study


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Compute UFP Case Study

Item Total Weight

External Inputs (EI) 32

External Outputs (EO) 19

External Inquiries (EQ) 18

Internal Logical Files (ILF) 30

External Interfaces (EIF) 0

Total (UFP) 99

Compute Degree of Influence


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Compute Degree of Influence

Compute the degree of influence / General

System Characteristics (GSCs)

NO. DI Factors Degree of Influence

(DI)

Remarks

1 Data Communications

2 Distributed Data Processing

3 Performance

4 Heavily Used Configuration

5 Transaction Rate

6 On-line Data Entry

7 End-User Efficiency

8 On-line Update

9 Complex Processing

10 Reusability

11 Installation Ease12 Operational Ease

13 Multiple Sites

14 Facilitate Change

Total degree of Influence (TDI)

Compute Technical Complexity Adjustment (TCA)


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Compute Technical Complexity Adjustment (TCA)

Compute the Technical Complexity Adjustment using thefollowing formula:

TCA = 0.65 + 0.01 * TDI

Case Study:

TCA = 0.65 + 0.01 * TDI

= 0.65+0

= 0.65

Compute Function Point Index (FPI)


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Compute Function Point Index (FPI)

Compute the Function Point Index (Size) using the followingformula

FPI = UFP * TCA

Add contingency factor

Case Study:

FPI = UFP * TCA

= 99*0.65

= round(64.35)

= 65

Compute Efforts


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Compute Efforts

Productivity ratio

No. of hours per function point Past data from Organizations

Reference Table

Sr. Environment User Interface Hours/Function Points(Industry Standard)

1. RDBMS(Oracle/Informix/Ingres)

Character Based 8 hours per function point2. RDBMS

(Oracle/Informix/Ingres)GUI based 12 hours per function point

3. COBOL Character Based 22 hours per Function Pointfor total efforts


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Rules of thumb (Person Days to Person Months)

8 hours per day

20 days per month

240 days per year

Mapping the efforts on to Schedule


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Mapping the efforts on to Schedule

Analysis 15%

High Level Design 15%

Low Level Design 10%

Coding 35%

Unit Testing 11%

Integration & System Testing 10%

Project Management 4%

Customer Acceptance Testing At actuals

Implementation At actuals

Warranty Support At actuals

Function Points for Enhancements


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Function Points for Enhancements

Function Points for enhancements Contd


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Function Points for enhancements Contd

Total Unadjusted FP before enhancements (UFP_tot_bef)

Total Unadjusted FP for changed functions before(UFP_chg_bef)

Total Unadjusted FP for deleted functions before(UFP_del_bef)

Technical Complexity Adjustment before (TCA_bef)

Total Unadjusted FP for changed functions after(UFP_chg_aft)

Total Unadjusted FP for functions added (UFP_add)

Technical Complexity Adjustment after (TCA_aft)

FPI = (UFP_add * TCA_aft) + 0.5 * (UFP_chg_aft * TCA_aft) +

0.25 * (UFP_del_bef * TCA_bef) +

(UFP_tot_bef - UFP_chg_bef - UFP_del_bef) *

(ABS(TCA_aft - TCA_bef)

Quick FPA


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Quick FPA

Carried out at a very early stage of the project

May be at the time of proposal preparation stage

Carried out because

Lack of time

Lack of information

Assumptions Difference between High and Low is not much, hence

average is used for calculation

Use a judgment call for overall complexity

Quick FPA - Calculation


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Quick FPA Calculation

Identify and count EIs, EOs, EQs, ILFs and EIFs

Do not count RETs, DETs and FTRs

Classify all functions as average

To calculate unadjusted function points, use the coefficients

EI 4 EO 5

EQ 4

ILF 10

EIF 7

VAF = 0.65 to 1.35

FPC = UFC * VAF

Quick FPA - Accuracy


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Quick FPA Accuracy

With all information Quick FPA gives a result which is + / -10 % of detailed FPA

It is INEFFECTIVE if used by persons who do not haveexpertise in detailed FPA

Case Study


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Case Study

Download following documents and calculate function points

Useful Sites/Contact Details


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Useful Sites/Contact Details

http://kms.techmahindra.com:6040/Pages/OrganizationalAssets.aspx

www.dacs.dtic.mil (Data & Analysis center for software)

www.ifpug.org (International Function Point User Group)

www.softwaremetrics.com

ftp://ftp.cms.livjm.ac.uk/pub/General/fpa.doc (Worddocument)

http://ourworld.compuserve.com/homepages/softcomp/fpfaq.htm (FAQ)

For queries, please contact Estimation Focus Group
http://kms.techmahindra.com:6040/Pages/OrganizationalAssets.aspxhttp://kms.techmahindra.com:6040/Pages/OrganizationalAssets.aspxhttp://kms.techmahindra.com:6040/Pages/OrganizationalAssets.aspxhttp://kms.techmahindra.com:6040/Pages/OrganizationalAssets.aspx

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FPA Mark I (AIT)

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