Software project estimation

Definition!
“Estimation determines how much money, effort, resources, and time it will
take to build a specific system or product.”

 For an effective management accurate estimation
of various measures is a must. With correct
estimation, managers can manage and control the
project more efficiently and effectively

Estimation is based on,
Past Data/Past Experience
Available Documents/Knowledge
Assumptions
Identified Risks

Four basic steps in Project Estimation are −
 Software size Estimation
 Software effort Estimation
 SoftwareTime estimation
 Software cost Estimation

Software size may be estimated
KLOC
Number Of Function Point

Effort estimation is calculated in Person-hour
Or person-days or Person-month.
For effort estimation software size should be
known.
software size can be converted into efforts by
using some standard formulas. e,g cocomo-II

 This might be considered as the most
difficult of all because it depends on more
elements than any of the previous ones. For
estimating project cost, it is required to
consider –
1) Size of Software
2) Software Quality
3) Hardware

4) Additional software or tools, licenses etc.
5) Skilled personnel with task-specific skills
6)Travel involved
7) Communication
8)Training and support

Project manager can estimate the listed
factors using two broadly recognized
techniques –
1) DecompositionTechnique
2) Empirical Estimation technique

 There are two main models -
1) Line of Code:
Estimation is done on behalf of number of
line of codes in the software product.
1) Function Points :
Estimation is done on behalf of number of
function points in the software product.

 This technique uses empirically derived formulae to
make estimation.These formulae are based on LOC
or FPs.
1) Putnam Model:
This model is made by Lawrence H. Putnam,
which is based on Norden’s frequency
distribution (Rayleigh curve). Putnam model
maps time and efforts required with
software size.

2) COCOMO-I:
COCOMO stands for COnstructive COst
MOdel, developed by BarryW. Boehm. It
divides the software product into three
categories of software: organic, semi-
detached and embedded.

1) Wideband Delphi Process
2) COCOMO-II
3) PROBE (Proxy based estimation)
4) PlanningGame

Software project estimation

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