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Basic Project Planning and Basic Project Planning and EstimationEstimation2/5/2007Keith Rome ([email protected])http://www.mindfusioncorp.com/weblog/
Have you ever been on a Have you ever been on a project that was "over project that was "over
budget" or "late"?budget" or "late"?
How could you tell?How could you tell?Constantly missing milestonesRising headcountCutting planned featuresLow quality (lack of sufficient QA)Poor architecture (not enough
time allotted)
Typical “Project Typical “Project Planning”…Planning”…Boss: "How long will that project
take?"Dev: "Two weeks I think."(two weeks later)Boss: "How's it coming? You done
yet?"Dev: "Just two more weeks..."(3 months later, the project is
terminated)
How to remedyHow to remedyUse objective estimates, not
subjective swags Document the level of "certainty" Factor in the expected planning
defects (requirements flaws, design gaps, etc)
Apply some basic math Identify Critical Paths and
slippage limits (slack) Refine as you go
PERT to the Rescue!PERT to the Rescue!Program Evaluation and Review Technique
First created in the 50’s to support R&D projects related to submarine missile programs
Objective estimatingObjective estimatingCan base on functional
componentsUsually correlated with a Work
Breakdown StructureTry to target blocks of work
roughly 1 day in durationUpdate requirements as
discrepencies are found (estimating is a good way to "proof" your requirements)
How "good" do you feel How "good" do you feel about the estimates?about the estimates?Rate each work item for how
accurate you think the estimate is
Give a reasonable Low and High estimate as well as the Likely
Good idea to also rate each item for subjective risk to project
Factor in global modifiersFactor in global modifiersPercentage of requirements
completionPercentage of requirements
defective / flawedPercentage of anticipated design gaps
(the things we know we don't know)Variable estimate accuracy
percentage (start at 100%)These will apply as global multipliers
to all estimates
Projecting the project Projecting the project timelinetimelineExpected = (Minimum + (4 *
Likely) + Maximum) / 6Plot out dependenciesAdd zero-duration work items for
start and finish eventsDetermine Early and Late Start
and Finish timesProject duration is equal to the
Finish time of the last task
Start and Finish timesStart and Finish timesEarly Start = maximum Early
Finish of all predecessorsEarly Finish = Early Start +
Expected DurationLate Finish = minimum Late Start
of all successorsLate Start = Late Finish -
Expected DurationSlack = Late Start - Early Start
Critical Path(s)Critical Path(s)Work Items on the critical path
always have Slack = 0Can be multiple critical pathsCritical paths can change when
work items slip or compactIn most situations, the critical
paths warrant the closest attention by management
Slippage limitsSlippage limitsSlack determines how far a given
task can be delayedDelay beyond the Slack estimate
will likely impact the critical pathSlack can be used to find
resourcing opportunities◦Move resources from high-slack
tasks to low-slack (critical path)◦Can help condense the overall
project delivery date
Measure and RefineMeasure and RefineTrack Actual times for each task
as they are completedUpdate the Variable estimate
accuracy percentage factorWatch out for shifts in critical
path
This process is methodology-This process is methodology-neutralneutralIncorporate into existing
management methodsEspecially suited for Iterative
WaterfallAlso can be useful with modified
RUP, MSF and Agile processes