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Function Point Estimation

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• Published : June 28, 2013

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Function Point Estimation
Function Point Estimation
1. What is Estimation? Estimation is the prediction of the future outcome based on some calculation and past experience. 2. Why do we do estimation? We do estimation for planning, tracking and schedule. A vehicle to estimate cost and resources required for software development and maintenance OR Following are the uses/benefits of FP Estimation:  Size  Productivity  Predicting Efforts  Resources  Understanding Unit Cost  Duration  Schedule 3. What is the objective of the function point estimation? Function point analysis measures software by quantifying the functionality of the software provided based primarily on logical design. With this in mind, the objectives of function point analysis are to: to the user

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Measure functionality that the user requests and receives Measure software development and maintenance independently of technology used for implementation

How to do estimation? I will cover that in a short while.

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When and where all in SDLC should we do estimation?  At the proposal state  At the project start stage  Whenever Changes occur  Phase wise  Project Close stage

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What is the estimation process?

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Size Productivity = -------------------Efforts

Note:              Function count can be used for the planning purpose. During the planning phase, we need to do so many things like preparing schedule, resource planning which will come from the size. All these things are interlinked. Function Point is the unit to measure the size of the software. If requirements are not clear then historical data can help in estimation. Estimation is done for both client as well as our self. Project contribution gives an idea of project profitability. We should re-estimate at the project start because: PM is not the one who gave the initial estimates at the time of proposal. So PM should also know the size of the project, which he is going to deliver. There might be some requirement change during the requirement analysis. During the estimation, we measure the functionality. Functionality is different from the implementation. When we put the functionality with productivity we get the efforts. Function Point includes the efforts of whole SDLC right from requirement to deployment. Productivity figure depends of company wise, technology wise etc. In Patni, J2EE projects productivity is around 0.9. On some projects productivity may go up to 4. Read about caper Jones for Industry data on measurement. If we know the timelines then we calculate the number of resources used in the project. Based on size we prepare the schedule.

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What is Function Point Analysis? Function Point Analysis is a method to break the system into smaller components to better understand and analyze the system. It is the standard method to measure the function or size the project. Function point is the unit of the functionality. Why do we use FP?

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Better understanding of the functionality. Better understanding of the application. When we want to size the application

Function Point Estimation in short…

Counting Elements: There are 3 things RET, DET and FTR that you need to count while doing the FP estimation. Let’s first understand what these elements are. RET (Record Element Type) When I was learning FP, RET was the most confusing and difficult concept. I took long time to understand this concept. Now let me try to put it in some simple words. This is a parent child relationship. Look at the customer data, now you can group the customer data based on the home

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address, work address, contact details etc. So, I would say that I would name all these grouping into separate RETs. However, when you can estimating you should not visualize it in form of tables. You just think that this is a...