Estimation is the process of approximating values even with incomplete or uncertain data. Software project estimation is challenging due to the complexity of software. Estimation is needed to allocate resources, bid for projects, and determine whether projects are done in-house or outsourced. Common project estimation approaches include analogous cost estimation, parametric estimation, three-point estimation, and bottom-up estimation. Wideband Delphi and planning poker involve expert panels providing multiple rounds of estimates. Work breakdown structures, PERT diagrams, and critical path methods break projects into tasks and dependencies. Guidelines recommend leveraging past experiences, including management time, using organizational data, and getting multiple estimates from developers using different techniques.

1. Estimation
Estimation is the process of finding an
estimate, or approximation, which is a
value that can be used for some purpose
even if input data may be incomplete
uncertain or unstable.

2. Project Estimation And Software Engineering
• Software engineers have very poor track record of estimating project
effort because software as product is very complex to measure and
estimate.
• We have just 50 YEARS of history to look back at softwares and get
some glimpse of shining north star of guidance.

3. Why We(software engineers) NEED to
estimate??
• Bosses needs estimates before allotting
resources.
• Software Firm has to put a bid for a project.
• Is it going to be in-house project or to
outsource?!
• Freelancing is all about estimating.

4. Project Estimation Approaches
• Analogous cost estimation
• Parametric Estimation
• Three-point Estimation
• Bottom-up Estimation

5. Wide Band Delphi
• Delphi Method is a structured
communication technique,
originally developed as a
systematic, interactive forecasting
method which relies on a panel of
experts. The experts answer
questionnaires in two or more
rounds. After each round, a
facilitator provides an anonymous
summary of the experts’ forecasts
from the previous round with the
reasons for their judgments.
Experts are then encouraged to
revise their earlier answers in light
of the replies of other members of
the panel.
• The term "wideband" is used
because, compared to the Delphi
Method the Wideband Delphi
Technique involved greater
interaction and more
communication between the
participants. In Wideband Delphi
Technique, the estimation team
comprise the project manager,
moderator, experts, and
representatives from the
development team, constituting a
3-7 member team.

6. Work Breakdown Structure
• WBS is a deliverable-oriented
decomposition of a project into
smaller components.
• WBS is represented as a
hierarchical list of project’s work
activities
• Precedence: A task that must occur
before another is said to have
precedence of
the other.
• Concurrence: Concurrent tasks are
those that can occur at the same
time .
• Critical Path: Specific set of
sequential tasks upon which the
project completion date depends.

7. PERT and CPM
•PERT is based on three values:
most optimistic estimate (O), a
most likely estimate (M),
and a pessimistic estimate (least
likely estimate (L)).
E = (O+4 × M+L)/6
• Critical Path Method (CPM) is
technique to arrange critical
project task in order and
hierarchy.

8. Planning Poker
• Planning Poker is a estimation
technique , mostly used to
estimate effort or relative size of
user stories in Scrum.
• Planning poker combines three
methods of estimation -
Expert Opinion
Analogy
Disaggregation

9. Estimation Guidelines
• During estimation, ask other people's experiences. Also, put your own
experiences at task.
• Include management time in any estimate.
• Where possible, use documented data from your organization’s similar past
projects.
• Always prefer developer-based estimates.
• Use several different people to estimate and use several different
estimation techniques.