Presenter – Tim Peek (TenStep)
Fear with estimates is that they will be inaccurate, but that’s just what an estimate is – a guess. You’ll only know if your estimate was right when you’re done.
A lot of the information to build estimates comes from historical data. Keep estimated vs. actual to determine estimation success
Estimates also give a yardstick as to how well you’re doing.
ROI is all about estimates, comparing the estimate to the value of the end product
Estimate is a judgment of size, number, etc. that needs assessment
Estimating is concerned with the prediction of uncertainties. It is more dignified than fortune telling, though not always more accurate.
- Project Estimating
- Effort (NOT duration)
- You can’t determine duration until you figure out the effort needed
- Cost
- Schedule
- Why is it important?
- Supports decision-making
- Provides an ability to deal with the unknown
- Determines what actions we see as safe and risky
- Hiring
- Spending
- Lifespan of equipment
- Preparing for the Estimate
- Determine estimating goals and tradeoffs
- Document the prior estimating assumptions and risks
- Distinguish between effort and duration
- I can have this activity done in 2 weeks.
- This activity will take 40 hours
- Levels of Accuracy
- Determine if there IS a level of accuracy requested or required (+/- 50%, SWAG, WAG)
- Estimate the Effort
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Estimate
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Accuracy
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Purpose
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Order of magnitude (Conceptual)
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-25%-+75%
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Evaluation of projects or alternatives
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Preliminary (Budget)
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-15%–+25%
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Establish initial budget, reserve funds for project
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Definitive
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–5%-+10%
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Establish actual project budget, after Project Charter
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- Preparing for the Estimate
- Avoid estimating what you do not understand or know
- Get a clear picture of the work you need to estimate
- Determine if full life-cycle costs are required
- Determine the resources covered in the estimate
- Immediate project team
- Clients
- Vendors
- Cross functional resources
- Estimating Techniques
- Previous History
- Analogy
- Ratio
- Expert Opinion
- Delphi – Group of Experts via Questionnaire
- Parametric Modeling
- Work Breakdown Structure
- PERT ((optimistic + 4x median + pessimistic)/6)
- Estimating Errors
- You underestimate the size of the deliverables
- You don’t include all of the activities required
- Documentation
- Project Management
- Training
- You commit to an estimate that is too low
- You estimate based on building good quality in the first time
- You do not manage quality, and don’t build quality control or QA activities into the schedule
- You have more testing errors and more rework required
- The client wants it done as quickly as possible
- Your manager wants it done as quickly as possible
- You think it can be done quickly, IF EVERYTHING GOES WELL
- You commit to an estimate based on best-case
- The client wants it done as quickly as possible
- The client has a fixed amount for the budget
- You think there is a chance you can get it done within available budget
- You commit to an estimate based on available funding
- The client tends to think the work is simple
- The workers think they can do more than they can
- The project manager does not take all the intangibles into account (estimating error, risks, problems, etc.)
- You underestimate the work
- You were burned on a similar project
- You really don’t want to do the work
- You tend to be pessimistic to begin with
- You overestimate the work and hope it gets cancelled
- Understanding common errors and not repeating them leads to more accurate estimates
- Estimating Effort, Duration and Cost
- Estimate effort hours first
- Duration estimates are next, based on known and unknown resources
- Cost estimates are created after the rest of the schedule is completed
- The Estimate is Too High
- The estimates are not arbitrary
- Ask for more time to do more accurate and detailed estimate
- You must balance the quality (effort), cost (budget), and time (schedule)
- Look for ways to reduce costs using same effort
- Less expensive resources
- Older equipment
- Internal instead of external training
- Look for ways to reduce effort while still delivering
- JAD sessions for requirements
- Outsourcing
- Look for ways to reduce the scope of work
- Cut out less important reqs
- Defer to later iteration
- Best Defense – Preparation
- The Estimating Packet
- You understanding of the work
- The process used to prepare the estimate
- The estimating technique(s) you used
- A summary of the estimate
- Effort, duration and cost as appropriate
- The level of uncertainty
- The estimating assumptions
- The detailed estimating information