Function point estimation

If the function points are clearly identified and defined, this technique can be considered as the most accurate one.

A function point is a unit of measurement used to know the amount of business functionality provided to the end user. Once the function is identified and categorized into a type, it is then assessed for complexity.

The Function Point Analysis is done using following requirements

Inputs
Outputs
Files
Inquires
Interfaces

Requirements	Simple	Average	Complex
Inputs	1	3	5
Outputs	2	4	6
Files	3	6	9
Inquires	2	4	6
Interfaces	3	5	7

Depending on the functional points for each case the above factor would be multiplies.

For example if there are 3 simple inputs then the factor would be 3 X 1 = 3.
Then project adjustment factor have to be calculated which is the sum of the below parameters.

Complex internal processing.
Code to be reusable.
High performance.
Multiple sites.
Distributed processing.

Productivity = No of outputs/ No of inputs.
Function Points = Productivity/ Inputs.
Adjustment calculation: Using this Adjusted FPs the final effort estimate would be calculated.

Test case point estimation

In this case, all the test cases that are to be executed should be finalized and approved by client. The number test cases are the main part of this technique. Each test case has to have a complexity defined as high, medium and simple. Now, the complexity and the no. of test cases along with the historic data of how many test cases can be executed by a resource for a day will be considered for the estimating the project.

This technique also require good amount of experience.

Now no. of test cases for each complexity should be calculated and for each complexity the amount of effort required should be defined and total effort will be calculated.

A buffer time will be added for the project management activities after the effort is arrived.

3 point estimation

3 point estimation is most widely used technique and has to be only done experienced people. In this technique the project or task is divided into sub modules or sub tasks. For each task 3 possibilities would be considered. They are

    a. worst case scenario.
    b. best case scenario.
    c. most likely scenario.

These can be defined depending on the experience of similar projects or past experience or historical data of the organization.

After arriving at the 3 values, the effort is calculated by averaging the worst case, best case and 4 times the most likely case.

The formula is

Effort = (best + 4 most likely + worst) / 6.

Why Estimations

Why Estimations?

    1. Estimating is mandatory task for any project or task as performing without any plan will not result in a quality output.

    2. Estimations provide predictability though they are not accurate in practical scenarios.

    3. The resources can be planned if estimations are in place.

    4. The cost of the project or task would be clear and can be projected to the management if estimations are done.

    5. Estimations form an input for the training plan and risk plan.