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Activity List

Resource Plan

Network Diagram

Integrated Schedule

Duration Estimate

Activity DefinitionActivity sequencingActivity ResourceEstimatingActivity Duration EstimatingScheduleDevelopment

#3PM3_T_B Planning TimeActivity Duration EstimatingActivity durations are the calendar time required to perform the workDuration comprises:Time spent by the resources actually performing the workQueue, wait or other inactive timesOther times required before the effort is complete (eg. Paint cure times, automated test run times)

#3PM3_T_B Planning TimeDuration Estimating TechniquesExpert judgment AnalogousParametricProbabilistic

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Expert JudgmentUsually performed bottom up, often in conjunction with cost estimates performed as part of the proposal processPerformed by experts:Functional leads/managersConsultants/SuppliersProject Management StaffAdvantages:Buy-in from performing staff and/or managementDetailed treatmentDisadvantages:Can be overly optimistic/pessimistic depending on estimator biasTendency to build in slack time

#3PM3_T_B Planning Time4If estimates are collected from the people doing the work, they will have a sense of commitment to make the estimate good. Shortcomings of this method include undue optimism or pessimism, gold plating, and failure to estimate the time required for integration of project components.

Analogous EstimatingUsually performed, Top down - a form of expert judgment that uses information from previous similar estimates to generate duration estimatesUsually performed by experienced project manager, manager, marketing personExample:Property X is a 6 story building which took 6 weeks to erect; property Y is a similar type of building with same foundation footprint and utilities, but 3 stories tall estimate it takes 3 weeks to erect Advantages:Quick, inexpensive estimate that can be performed before product team is assignedCan be applied to even relatively poorly defined activitiesDisadvantages:Only useful when projects are similar in fact, not just in appearance (eg. Property X built in Toronto, Property Y built in Greenland)Difficult to apply to lower level tasks

#3PM3_T_B Planning Time5Even if all the other conditions are met, then and now can be very different, particularly in areas of rapidly advancing technology.

EXAMPLE: In 1999 it took four weeks to prepare and print a new book and required the printing of a few thousand copies to be economical. In 2002 it takes two weeks and printing a single copy is now economical.

Parametric EstimatingUsed for repetitive tasks where metrics are maintainedNumber of engineering drawingsSquare feet of constructionLines of programming codeExample:SW Coding=4 hours/line of codeAdvantages:Quick and easy to useCan draw on Industry standard handbooks which base estimates on broad data sets (eg. Construction estimating guides)DisadvantagesMost project work does not fall into this categoryOnly applicable where large data sets are available, yielding relevant averages

#3PM3_T_B Planning Time6Quantitatively based estimates are estimates based on parametric analysis. If brick can be laid at the rate of 24 per hour and 4,800 brick are required, the task will take 200 hours.

Example: SW Lines of Code

Estimated Development Effort:(Basic COCOMO model, Person-Months = 2.4 * (KSLOC**1.05)) Estimated Schedule:(Basic COCOMO model, Months = 2.5 * (person-months**0.38))

#3PM3_T_B Planning TimeProbabilistic EstimatingThe methods so far produce Deterministic estimatesUseful if the duration is known with a fair amount of certainty (eg. Time to produce a test report)For most estimates, the duration is uncertain (eg. Time to run the test: what if it fails? No equipment? Equipment fails? Etc.) in this case, need some way to account for the probability of things going better or worse than plannedTwo methods of accounting for uncertainty:Weighted average estimateThree point estimate used in schedule risk simulation

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Weighted Average EstimatesProbability follows a distribution (eg. For most naturally occuring phenomena = the normal distribution or bell curve)Activity durations do not typically follow a normal distributionleft skewed ie. The difference between the soonest completion and the most likely completion date is smaller than between the mostly likely date and the latest completion early studies by US DoD lead to adoption of a triangular distribution called the PERT distribution because it was used in the Program Evaluation and Review Technique concurrently developedA single point estimate for a PERT distributed task is

Where to , tm , and tp are the optimistic, most likely and pessimistic estimates

Example: a test usually takes 2 days to set up and run; if setup goes smoother than usual it takes 1 day; if the test equipment breaks down and needs maintenance, it takes 5 days for this, and the initial 2 days for set up and running = 7 daysto +4 tm + tp6

to tm tp1 +4x2 + 76Estimated duration = = 2.4 days

to tm tp

Estimatedduration

#3PM3_T_B Planning TimeSchedule Risk ModellingStatistical techniques used to model entire schedule based on multiple duration estimates for each taskEg. Monte Carlo analysisto , tm , and tp are input into a random number generator which produces an estimated time for each task Sample total schedule duration is calculated by applying sequence logicProcess is iterated until a steady distribution of final durations is modelled

#3PM3_T_B Planning TimeAdding Schedule DurationEntering into the Activity List

Entering into the Task Info box

#3PM3_T_B Planning TimeSchedule Leads and LagsTechnique that introduces a time delay to a sequencing relationship to add realistic timing without unnecessary tasksEg. Allow time for the customer to approve test results add a lag = 36FS+4d, the phone call will now happen 1d after the paperwork startsMust exercise caution not to replace actual work with a lag (eg. Time between work completion and shipment may include test, inspect, paperwork these should be tasks)

#3PM3_T_B Planning TimeTypical Activity Duration Estimating ProcedureDuring proposal phase, the proposal manager and/or project manager produces a high level schedule based on an analagous estimateDuring the preliminary planning phase, detailed activity duration estimates are developed by team leads using expert knowledge and parametric estimating where possibleUpon review of the preliminary schedule, critical and near-critical paths may be subjected to risk modelling to identify areas for mitigation planning, and possible schedule reserve allowancesDuring project execution, team leads revise duration estimates using expert knowledge modified by analagous estimating drawn from project experience to date

#3PM3_T_B Planning TimeSheet1LanguageSLOC (%)C21461450 (71.18%)C++4575907 (15.18%)Shell (Bourne-like)793238 (2.63%)Lisp722430 (2.40%)Assembly565536 (1.88%)Perl562900 (1.87%)Fortran493297 (1.64%)Python285050 (0.95%)Tcl213014 (0.71%)Java147285 (0.49%)yacc/bison122325 (0.41%)Expect103701 (0.34%)lex/flex41967 (0.14%)awk/gawk17431 (0.06%)Objective-C14645 (0.05%)Ada13200 (0.04%)C shell10753 (0.04%)Pascal4045 (0.01%)sed3940 (0.01%)ProductSLOCNASA Space Shuttle flight control420K (shuttle) + 1.4 million (ground)Sun Solaris (1998-2000)7-8 millionMicrosoft Windows 3.1 (1992)3 millionMicrosoft Windows 9515 millionMicrosoft Windows 9818 millionMicrosoft Windows NT (1992)4 millionMicrosoft Windows NT 5.0 (as of 1998)20 millionRed Hat Linux 6.2 (2000)17 million

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