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SOFTWARE DEADLINE TIMEESTIMATION
BY Tutunaru DANIEL
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SOFTWARE ESTIMATION
• Is done often because it is expected to help in
predicting how much will the project cost and
when will the project get completed.
• It is important, especially at the time of
bidding for project, and establishing
deadlines.
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Elements of a Successful Estimate (1)
• An estimation starts with a work breakdown
structure (WBS).
• A WBS is a list of tasks that, if completed, will
produce the final product.
• The way the work is broken down dictates
how it will be done. There are many ways to
decompose a project into tasks.
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Elements of a Successful Estimate (2)
• The project can be broken down by feature, by
project phase (requirements tasks, design
tasks, programming tasks, etc.), or by some
combination of the two.
• Ideally, the WBS should reflect the way
previous projects have been developed.
• A useful rule is that any project can be broken
down into 10 up to 20 tasks.
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Elements of a Successful Estimate (3)
• Once the WBS is created, the team must create anestimate of the effort required to perform each task.
• The most accurate estimates are those that rely onprior experience.
• Team members should review previous project resultsand find how long similar tasks in previous projectstook to complete.
•
Sources of delays in the past should be taken intoaccount when making current estimates.
• Postmortem reports are a good source of thisinformation.
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Elements of a Successful Estimate (4)
• No estimate is guaranteed to be accurate.
• People get sick or leave the organization; teamsrun into technical problems; the needs of the
organization change.• The unexpected will almost certainly happen.
• Therefore, the goal of estimation is not to predictthe future. Instead, it is to gauge an honest, well-informed opinion of the effort required to do atask from those people in the organization whohave the most applicable training and knowledge.
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Software Project Estimation is
Inherently Inaccurate (1)
• Because:
1) No one asked the people who are in-chargeof doing the task for their estimates.
2) Resources are fixed, but a deadline is set.
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Software Project Estimation is
Inherently Inaccurate (2)
• The Triangle of Constraints states
that in a project there are three
constraints, Scope, Time, and
Cost, if one of the constraintschanges, then so will the others.
• In this case, if the deadline is set,
time is fixed. Therefore, either
scope has to be reduced or thecost needs to go up or maybe
both scope and cost will change.
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3 Ways to Meet Software Project
Deadline
• Simplify Over-engineered Designs
• Simplify Features
• Cut Low Priority Features
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SOFTWARE PROJECT DEADLINE
ESTIMATION METHODES
• Wideband Delphi Estimation
•
Proxy Based Estimating (PROBE)
• The Constructive Cost Model (COCOMO)
• The Planning Game
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DEADLINE AS ESTIMATED DATE OF
COMPLETION (EDC) (1)
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DEADLINE AS ESTIMATED DATE OF
COMPLETION (EDC) (2)
• Figure : -The Optimistic
-Most Likely
-Pessimistic-Expected Times for Project
Completion
• The expected time for work completion, E isE = ( O + 4M + P ) / 6
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THE CASE FOR A RELAXED INITIAL EDC
(1)
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THE CASE FOR A RELAXED INITIAL EDC
(2)
• Figure : The expected time for project with
provision of error in estimation.
• E' is the EDC for the project, taking into
account the errors in estimation for software
development work.
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CONCLUSIONS
• Many software projects end up as failuresbecause of tight deadlines.
• A deadline is an estimate for completion of
development work.• Since it is an estimate made before starting the
work, there is an associated probability that thework will actually get completed by the estimated
deadline.• An alternative term for deadline is the estimated
date of completion (EDC) of a project.