fp estimation

8/4/2019 FP Estimation

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Function Point Estimation

1. FP : Function Point

2. ILF : Internal Logical File.

3. EIF : External Interface file

4. EI : External Inputs

5. EO : External Outputs

6. EQ : External Enquiries

7. RET : Record Element Type

8. DET : Data Element Type

9. FTR : File Type Reference


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10. GSC : General System Characteristic

11. VAF : Value Added Factor12. LOC : Line of code


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1.Interna ogica i e ILF : T is contains ogica y re ate ata t at resi es insi e app ication oun ary. T e

application has to maintain data . Example like customer table which will be maintained through a Customer

data entry screen. Note the inside application data is updated and not any external data. But if you are updating

external application table, those tables will not be categorized as ILF.

This contains components which will lie external of application boundary and used for only for reference

purpose. Note : Do not include functionality like updating the external application in this section

EI is basically from which we can maintain the ILF. Accountants definitely should have interface through which

they can maintain (Add, Update, Delete) the customer ILF. The basic judgment factor to come out with EI is from

user screens. Like, a customer maintenance screen which gives us an idea that we have 1 EI and 1 ILF of

customer.

Here data passes from inside application to outside. Example your application generates XML or CSV ( Comma

separated values) Files. These files are then used by some external application to update the external application

tables. So in this scenario the data is passed from your application to a external application. So these types of

function will fall in this category.

When you send data to external application if you are getting some output from external application. Later this

output is updated in the ILF of internal application is also scenarios which will come under EO.

So litmus test for identifying EO's are :-

a) When data crosses boundary and goes and updates external application tables(EIF).

b) In response of you data sent you get some derived data which is updated in the internal application(ILF).

These functions will be mainly reports. They have input criteria. Any type of reports and search screens are right

components for EQ.Note like EI and EQ they do not update any ILF or EIF.They only fetch data for display. So the

litmus test for identifying EQ is any reports or search screens which do not update data in any tables(ILF or

EIF).Example Balance sheet in accounting reports.A subgroup of data element inside a logical file. In our customer ILF, we can have multiple addresses or multiple

phone numbers. So for the customer, we can have 2 RETs, Addresses and Phone numbers.

DET is a non-repetitive field in a ILF. Please note, I have said that field should not repeat in counting again. Every

customer ILF can have Customer Code. So the customer code becomes a DET. Every invoice can have customer

code saying whom this invoice belongs to. But once the customer code has been counted, do not count

customer code twice as two different DETs. But in practical scenarios, when doing function point of huge

projects, there is possibility that you can count DET twice, make a second iteration just for removing the

duplicate DETs.

An FTR is a file referenced by transaction. An FTR must also be an internal logical file or external interface file.


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This section is the most important section. All the above 3 sections are counting sections. They relate only to

application. But there are other things also to be considered while making a software, like are you going to make

it an N-Tier application, what's the performance level the user is expecting etc. These are external factors which

affect the software a lot and also the cost of it. When you submit a function point to a client, he normally will

skip everything and come to GSC first. GSC gives us something called as VAF (Value Added Factor). There are 14

points considered to come out with VAF (Value Added factor).

1.Data communications: How many communication facilities are there to aid in the transfer or exchange of

information with the application or system?

2.Distributed data processing: How are distributed data and processing functions handled?

3.Performance: Did the user require response time or throughput?

4.Heavily used configuration: How heavily used is the current hardware platform where the application will be

executed?

5.Transaction rate: How frequently are transactions executed; daily, weekly, monthly, etc.?

6.On-Line data entry: What percentage of the information is entered On-Line?

7.End-user efficiency: Was the application designed for end-user efficiency?

8.On-Line update: How many ILFs are updated by On-Line transaction?

9.Complex processing: Does the application have extensive logical or mathematical processing?

10.Reusability: Was the application developed to meet one or many users needs?

11.Installation ease: How difficult is conversion and installation?

12.Operational ease: How effective and/or automated are start-up, back up, and recovery procedures?

13.Multiple sites: Was the application specifically designed, developed, and supported to be installed at multiple

sites for multiple organizations?

14.Facilitate change: Was the application specifically designed, developed, and supported to facilitate change?

All the GSC have ratings from 0 to 5. So, the VAF formulae is something like this:

VAF = 0.65 + ((sum of all GSC factor)/100).


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Transaction Section:

Transaction section uses data

section, that is, it maintains

information of ILF and EIF.

Excuse me for the short

acronyms I am using

everywhere, like the ILF and

EIF there's acronym list at top

for everything. All the down 3

components

adds,modifies,deletes,retrieve

s or process information

contained in ILF and EIF so are

termed as Transaction Section.


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Less than 2 3 3 4

2 3 4 6

>2 4 6 6

FTR 1 to 5 19-Jun >19

< 2 4 4 5

2 or 3 4 5 7

>3 5 7 7

FTR 1 to 5 19-Jun >19

< 2 3 3 4

2 or 3 3 4 6

>3 4 6 6

RET 1 to 19 20-50

51 or

more

1 RET 7 7 10

2 to 5 7 10 15

>6 10 15 15

RET 1 to 19 20-50

51 or

more

1 RET 5 5 7

2 to 5 5 7 10

>6 7 10 10

Section RETs FTRs DETs

EI 1 1

EO 1 1

Data Elements

EI Rating Table

Data Elements

FTR 1 to 4 15-May >15

EO Rating Table

Data Elements

EQ Rating Table

Data Elements

ILF Rating Table

EIF Rating Table

Data Elements

every transaction which subsection is eligible.If you


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EQ 1 1

EIF 1 1

ILF 1 1

Simple Customer Project

Simple Customer Project

This is a simple project requirement where we are supposed only to do the customer form and w

There are 2 ILFs in the above screen:

1. The customer ILF.

2. The Customer Address ILF.

There are no EIFs in the above form.

Description Number of DETNumberof RET

ILF Customer


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There are total

10 DETs, all add

and update

buttons, even the

credit check

button, the

address list box,

check box active,all text boxes.

There is only one

RET, the

customer

addresses. Note i

have not included

the credit check

as RET as they

are not Sub-

elements(Childelements of

Customer ILF).

So according to

the above ILF

rankin table

Total function 7

Description Number of DET

Number

of RET

There are total 3

DETs, all the

column names in

the list box, city

name, street

name and pin

For the customer

address ILF there

are no RET.Please

note if this

customer address

screen is any

where else and

they have RET

then make

changes

accordingly.

Total FP 7


Number

of RET

10 1

ILF Customer addresses

3 0

EIF Credit card Information


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The credit card

information

referenced is

EIF.Note this file

is only referenced

for credit card

check.

There's only one

textbox credit

card number and

hence one DET is

put in the side

column. and RET

0.Looking at the

above rating

table the total FP

is 5.

Total FP 5


Number

of FTR

There are total

10 DETs, all add

and update

buttons, even the

credit check

button, the

address list box,

check box active,all text boxes.

There are 2 FTRs,

one is the

address and the

second is the

credit card

Referring ranking

table above

Total Function 4

While counting EI i have seen many people multiplying it by 3.That means we are going to do all

EO Customer

EI Customer

10 2

1 0


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No EO for this

screen. As

Customer system

is not sending

any information

to external

system which will

add or update the

external system.

EQ Customer

screen.At this

moment there is

no reports

section

here.Please note

the display of

cutomer

addresses is notcounted as EQ.

So now, let's add the total function point got from above tables :

Section Name

Function Point

Counted

ILF Customer 7

ILF Customer

Address 7

EIF credit card

information 5EI Customer 5

Total

Unadjusted

Function Points 24

So all function point comes to 24.Please note i have said this as Unadjusted function as we have

In order to make it adjusted function point, we have to calculate and tabulate the GSC and com

GSC Value(0-5)

Data

communications 1

Distri ute ata

processing 1

Performance 4

Heavi y use

configuration 0


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Transaction rate 1

On-Line ata

entry 0

End-user

efficiency 4

On-Line update 0

Comp exprocessing 0

Reusability 3

Installation ease 4

Operational ease 4

Multiple sites 0

Facilitate change 0

Total 22

So using formulae:

ollapse | Copy Code

VAF = 0.65 + ((sum of all GSC factor)/100). = 0.65 + (22/100) = 0.87.

This factor affects the whole FP like anything, be very particular with this factor. So now, calcula

adjusted FP = VAF * Total unadjusted

FP = 0.87 * 24 = 20.88 = rounded to 21 FP.

Now we know that the complete FP for the customer GUI is 21 FP. Now calculating the efficiency


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ith address details of it. Following is the screen.


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l CRUD functionality(ADD,UPDATE,DELETE).This is not fair as it just shows laziness of the Co


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not accounted other variance factor of project (Programmers leaving job, Language we will

out with the VAF.


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ting the

factor, we say that we will complete 3 FP per day, that is 7 working days. So, the whole cus


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st estimation team. Here the customer screen has add and update. I can say the 2 * 4 that'


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use, What architecture etc etc).


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tomer GUI is of 7 working days (Note do not consider Saturday and Sundays in this). I kno


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= 8 FP for this EI customer. But i adjust this factor in my buffer. If you start multiplying fo


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upper manager people will say make it 7 FP per day and over load the programmer. Thats


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r every master screen like this it will be not fair for the customer. So make a genuine count


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hy programmer works at night.


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t the first half and later in buffer add the extra FPs.So over here i count this as 1 EI and not


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multiply by any factor.

fp estimation

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