Vladimir Liberzon, PMPSpider Project Team
Moscow, Russia PMI Chapter
Application of SDPM approach
to managing EPC projects
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HistorySuccess Driven Project Management (SDPM)
methodology was developed in Russia in 90-s and since then was successfully used in many projects, programs, and organizations and not only in Russia
Two years ago its implementation in Petrobras (Brazil) was presented at PMI COS Conference in Chicago
Last year its application for management of 2000 projects portfolio of Romtelecom (Romanian Telecom company) was presented at PMI COS Conference in Boston
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HistorySDPM is supported by Russian PM software
Spider Project but its basic approaches can be used with other PM software tools
Success Driven Project Management methodology has some common features with Critical Chain Project Management approaches but many differences too
Application of SDPM approaches showed very good results and the number of companies that implement SDPM is growing very fast
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SDPM IdeasTriple constraint and multiple project success
criteria make project management too complicated. There is a need in the single and integrated project success criterion.
Single project schedule and budget for all project stakeholders leads to project failure. There is a need for setting different targets for project work force, for project management team, and project sponsor.
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SDPM IdeasProject schedule and budget for project team
members shall be optimistic (no reserves included), project targets (scope, time, cost) for project management team shall include contingency reserves for known unknowns, project sponsor targets shall include management reserves for unknown unknowns. All these targets shall be set for internal plans.
Contract targets shall include additional reserves to ensure its successful performance and future profit.
Managing several schedule models in parallel is a part of SDPM approach.
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SDPM IdeasProject management team shall have time and
cost buffers for managing project risks and uncertainties. These buffers are not connected with any activity sequence. Project buffer is a difference between target value and the value for the same parameter in the working schedule.
Targets shall be set using risk simulation. These targets shall have reasonable probabilities to be met. Risk simulation shall calculate necessary project cost and time buffers.
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SDPM IdeasProject status information is useful but not sufficient
for decision making. Decision making shall be based on the analysis of project trends.
Project buffers will be consumed during project performance. Project management is about managing these buffers. If they will remain positive to the moment of project finish then project management was successful and the targets were reached.
There is a need to have tools for measuring project buffer penetration and project performance analysis. The best indicator of buffer penetration and project performance status is current probability to meet project target.
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SDPM IdeasIf the probability to meet project target is rising
then project buffer was consumed slower than we expected, in other case project buffer was consumed too fast and project success is endangered.
Success probability trends are the best integrated performance indicators – they take into account project risks, they depend not only on performance results but also on the project environment.
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SDPMSDPM methodology also includes approaches to
creating project schedule models and organizing project data.
In this presentation we will discuss:Organizing project data in EPC projectsResource Constrained Scheduling and Resource
Critical Path,Risk Simulation methods and objectives,Setting right project goals,Setting and managing Project Buffers,Success Probabilities,Management by Trends
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Data Structure
The main elements of any project schedule model include:project activities,activity dependencies,resources,resource assignments,calendars,costs,Work, Resource and Cost Breakdown Structures.
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Activities
In the majority of well-known PM software packages project activities are characterized by their duration or effort.
But in most construction projects it is necessary to set the activity’s physical volume (quantity) of work.
Activity volume can be measured in physical units (meters, tons, etc.) or planned work hours.
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Activities
Activity volume is often used as an initial activity information instead of duration.
If assigned resource productivity is defined in volume units per hour then activity duration may be calculated during project scheduling.
Unlike activity duration activity volume does not depend on assigned resources.
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Dependencies
Special Requirements:o It is necessary to be able to set more than one
link between two activities.o Besides the positive and negative time lags, it is
useful to set volume lags, that is preferable in many cases.
One of the potential problems with time lags is that slower performance of the preceding activity may lead to time lag too early completion when expected volume of work was not done. The time lags call for special attention and regular adjustments.
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Resources
Resources are divided into two classes: renewable (human resources and mechanisms) and consumable (materials, equipment).
In our software they are not just resource types, but different objects (Resources and Materials).
It makes possible to define that renewable resources consume materials during their work (car consumes gas, etc.).
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Complex Resources
Besides the individual resources it is useful to set resource crews (we call them multi-resources) and resource skills (roles).
Multi-resource is the settled group of resources working together (e.g. a team, a crew, a car with a driver, etc.).
Multi-resource can be assigned to activity which means an assignment of all resources comprising the multi-resource.
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Resource Skills
Resources belong to the same Skill set If they can do the same types of work (share the same skill).
Resources belonging to the same Resource Assignment Skill are interchangeable though individual resources may have the same skills but different productivities performing the same activities.
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Calendars
Different calendars can be set for all activities, resources and time lags.
Availability of all these calendars is important for the proper project simulation.
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Resource Assignments
Assigning resources to activities implies the notion of a team - a group of resources working on an activity together.
The team can include individual resources, multi-resources and skills.
Resources belonging to different teams can work at different time periods. Teams work independently of each other.
Example: resources that work in different shifts belong to different teams.
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Resource Assignments
If activity’s initial information is work volume, one should set the productivity of at least one of assigned resources to enable the calculation of the activity duration.
It should be noted that when the skills are assigned, activity duration can be calculated only in the process of scheduling when assigned resources are selected from the skill set.
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Resource Assignments
When assigning resource skills, one should either set a total number of resources necessary for activity execution or their total productivity.
Example: a skill set consists of the trucks with different carrying capacity. One may set a number of trucks necessary for the activity execution or the total productivity (dependent on capacities) of all assigned trucks.
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Resource Assignments
Resources can be assigned to activities part time. In this case one shall set percentage of assigned
resources utilization (resource workload) together with resource quantity (not just the total percentage calculated by multiplying percents and quantities, that leaves the necessary amount of resources unclear - two resource units with 50% utilization are equivalent to one resource unit used to its full capacity).
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Resource Assignments
Another useful option – variable resource assignments.
Example: You may define that the number of resources that
may be used at some work is between 2 and 4, and their workload should be not less than 40% and not more than 80%.
In this case an activity will start if two units of assigned resource are available not less than 40% of their work time, and the team may be increased if additional resources become available. Finishing other assignments resources may apply more of their time to the specified assignment but not more than 80%.
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Material assignments
Resources can consume materials in the process of their work, so materials may be assigned to resources.
Besides materials can be assigned to activities or resource assignments directly. Material assignments may be defined as fixed quantities, or quantities per hour or volume unit.
In some projects it is necessary to simulate not only material consumption but also production of resources and materials on activities and assignments.
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Cost
Usually it is not enough just to define activity and resource costs. It is necessary to know project expenses and revenues, what will be spent on wages, on machinery and equipment, on taxes, etc.
Sometimes it is necessary to allow for multiple currencies. So there is a need to define and assign cost components. Besides setting the cost of an hour of renewable resource
work and the cost of material unit, it is necessary to be able to set the cost directly for activities and assignments.
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Cost
People may be paid not only for the hours spent on the task but also for the quantity of work they have done.
It means that labour resource cost that is usually defined by the cost of work hour is not enough.
Frequently it is necessary to set costs for resource assignments (fixed or per unit of volume).
Assignment cost is an example of setting contract costs for the project activities.
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Centres
It may be necessary to get different reports on the groups of cost components, materials and resources. That is why Cost, Material and Resource Breakdown Structures and Centres are created and used.
Material centre can include any group of materials. Resource centre can include any group of
resources. Cost centre includes selected cost components.
EPC ProgramsEPC projects are usually large and consist of
several subprojects managed by different teams.EPC projects shall be called Programs and
further in this presentation we will use this term.Program management may be efficient if all
projects of the program are managed in the coordinated way, using the same approaches to creating schedule models, the same cost components, the same coding structures, the same estimates of the similar works, etc.
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Program Management requirements
Program Management requirements to the data that are used for project planning and control may be divided into two main groups:High level requirements based on the program
management needsLow level requirements that shall be applied to
creating project schedule modelsHigh level requirements consider data organization
that shall be the same for all projects of the program
Low level requirements cover details and instructions on creating project schedule models31
The same Project, Phase, Activity, Resource, Material, and Department coding structures shall be used in all projects
Resources that are used in all projects shall belong to the program resource pool
Resources of the same type share the same characteristics (like cost, productivities on the same assignments, material consumption per work hour)
Program Management requirements
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WBS structures that are used in similar projects shall be developed based on the same templates
Project costs shall have the same structure in all projects (same cost components are used)
Cost accounts are the same in all projectsActivities of the same type have the same
characteristics in all projects (like unit cost, material requirements per work volume unit, etc.)
Program Management requirements
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Typical resource assignments have the same characteristics in all projects (like productivity, cost and material requirements per work volume unit)
The same types of activities planned to be performed by the same crews
Typical (repeating) processes are modeled in the same way in all projects
Project archives are kept and stored as required
Program Management requirements
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These requirements shall be set on the Program level and are mandatory for all projects in the program including those that are managed by subcontractors
Templates, reference-books, coding systems etc. are developed in the Program Management Office
Program Management Office creates Databases (or Reference-books) that contain those parameters that shall be used for planning of all projects of the Program
Organizing data
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Program Reference-books usually include:Activity cost and material requirements per volume (quantity
of work) unit for all activity types (activity unit cost and material consumption)
Resource assignment cost and material requirements per volume unit for all assignment types (activity unit cost and material consumption)
Resource assignment productivities for all assignment types,Resource assignment workloads for all assignment types.
Activities, resources and resource assignments belong to the same type if they share the same characteristics.
Corporate Databases(Reference-Books)
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Resource AssignmentProductivities and Material RequirementsPer Volume Unit on theRoad construction
Examples of the Reference-books
Project fragments usually describe typical processes and technologies that are used more than once as small projects.
Creating project schedule models using the library of typical fragments helps to avoid inconsistencies and assures that the project model follows Program standards.
A library of typical fragments is very important tool for the development of common culture and management standards.
An example of Typical Fragment model is shown on the next slide.
Typical Fragment Library
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Project Management Guidelines
Program management has to be based on the program standards. These standards include not only estimates of the typical process, activity, resource, and assignment parameters but also project templates.
Besides, Program Management Guidelines developed in the Program Management Office describe Program management routine (when and what reports shall be presented, performance review meetings schedule, etc.) and change management processes.
This slide shows WBS template for sport objects construction projects required by Program Management Office of Sochi 2014 Olympic Games EPC Contractor.
WBS Template
Multiple WBS
It is useful to have an opportunity to get project reports that aggregate project data different ways. Usually we use at least three Work Breakdown Structures in our projects: based on project deliverables, project processes and responsibilities.
At least one WBS is mandatory and required by Project Management Office. Others may be selected by project management teams.
Contract Breakdown Structure is the powerful tool for management of contract relationships. The same contractors may be involved in multiple projects.
Contract Breakdown Structures are used to get reports on the contract performance and contract cash flows.
Contract Breakdown Structure
Cost Breakdown Structure
Cost Breakdown Structure for contract costs is defined by Program Management Office.
Contractors can add cost components and create Cost centers for planning and tracking their real expenses.
It is necessary to manage not only expenses but also financing.
Program managers control program, project and contract cash flows.
It is necessary to keep project schedule archives to be able to restore and analyze trends of project parameters.
If project schedule archives are available it is possible to compare current project schedule with the schedules created one week ago, one month ago, etc.
It is also useful for conflict resolutions
Project Archives
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Project scheduling without resource limitations taken into the consideration,
Project/Portfolio resource constrained scheduling (resource leveling),
Calculation of feasible activity floats and those activities that are critical,
Calculation of the Project/Portfolio cost, material and resource requirements for any time period.
Scheduling Tasks
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The problem of project schedule development without allowing for resource constraints has a correct mathematical solution (Critical Path Method), which would be the same for all PM packages, provided that initial data are identical.
Other tasks are solved using different approaches and yielding different results.
Critical Path Method
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Resource constrained scheduling
Resource constrained schedules produced by different PM software are different. The software that calculates shorter resource constrained schedules may save a fortune to its users.
Simple heuristics used by most PM software does not guarantee satisfactory resource constrained scheduling results.
That is why we pay most attention to resource-constrained schedule optimization.
Resource constrained scheduling
This is one example of very simple project but resource constrained schedules created by most PM software for this project are at least two weeks late.
The schedule stability is no less important, especially at the project execution phase
That is why our project management software Spider Project features an additional leveling option - the support of the earlier project version schedule (keeping the order of activity execution the same as in selected earlier project schedule)
Resource constrained scheduling
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Traditional notion of Critical Path works only in case of unlimited resources availability.
Let us consider a simple project consisting of five activities, presented at the next slide.
Activities 2 and 5 are performed by the same resource.
Sample Project before leveling
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Please pay attention to activities that became critical. Now delaying each of the activities 1, 2 and 5 will delay the project finish date.
We call these activities Resource Critical and their sequence comprises Resource Critical Path.
Sample Project after leveling
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In many projects it is necessary to simulate financing and production, and to calculate project schedules taking into account all limitations (including availability of renewable resources, material supply and financing schedules).
True critical path should account for all schedule constraints including resource and financial limitations.
We call it Resource Critical Path (RCP) to distinguish it from the traditional interpretation of the critical path definition.
Resource Critical Path
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The calculation of RCP is similar to the calculation of the traditional critical path with the exception that both early and late dates (and corresponding activity floats) are calculated during forward and backward resource (and material, and cost) levelling.
This technique permits to determine feasible resource constrained floats.
Activity resource constrained float shows the period for which activity execution may be delayed within the current schedule and with the set of resources available in this project without delaying project finish.
Resource Critical Path
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As you may notice in our example, Resource Critical Path may include activities that are not linked with logical dependencies.
Resource Critical Path is actually not the path but the longest sequence of activities in the current schedule.
One activity may depend on another because these activities are performed by the same resources. We call these dependencies as Resource dependencies.
Resource dependencies may be shown in the project schedule with the dotted arrows but they are the result of the project levelling and not initial information like logical dependencies.
Resource Critical Path
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If project success criteria are set as finishing project on time and under budget then proper decision making will be complicated.
For example, project managers will not be able to estimate if their decisions to spend more money and finish the project earlier are reasonable.
We suggest to set one integrated criterion of the project/program success or failure.
Project Success Criteria
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EPC program completion delay usually means huge money loss.
For the Client it means the loss of the profit that may be received at that time
For Contractor it means an increase of indirect costs together with contract penalties
In any case the delay of any project finish date usually increases project indirect cost, and acceleration means saving money
EPC Program Success Criteria
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So each day of program delay means some money losses and finishing program earlier means additional profit for all program participants
We suggest to define the cost of a project/program day (maybe separate and different for acceleration and delay) estimating these profits and losses
This way we define the rules of the game that is called EPC Program Management
EPC Program Success Criteria
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Our experience in project planning shows that the probability of successful implementation of deterministic project schedules and budgets is very low.
Therefore project and program planning technology should always include risk simulation for calculation of necessary contingency reserves and setting achievable targets.
Why risk analysis?
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Risk simulation may be based on Monte Carlo simulation or use three scenarios approach.
We prefer 3 scenario approach for the reasons explained further.
Risk Simulation
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A project planner obtains three estimates (optimistic, most probable and pessimistic) for all initial project data (duration, volumes, productivity, calendars, costs, etc.) and creates optimistic, most probable and pessimistic scenarios of project performance
Risk events are selected and ranked using the usual approach to risk qualitative analysis
Usually we recommend to include risk events with the probability exceeding 90% in the optimistic scenario, exceeding 50% in the most probable scenario, and all selected risks in the pessimistic scenario
Risk Simulation – three scenarios approach
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Most probable and pessimistic project scenarios may contain additional activities and costs due to corresponding risk events and may employ additional resources and different calendars.
As the result project planner obtains three expected finish dates, costs and material consumptions for all project phases and the project as a whole.
They are used to rebuild probability curves for the dates, costs and material requirements.
Risk Simulation – three scenarios approach
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If probability curve is known the required probability to meet project target defines the target that shall be set.
The area under the probability curve to the left of the target value determines the probability to meet the target.
P=S(blue)/S(whole)
Risk Simulation – three scenarios approach
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Target dates of most projects usually are predefined. They may be set not only for the whole program/projects but also for their major phases.
Project planning includes determining how to organize the execution to be able to meet required target dates with the reasonable probability.
Project/Program Targets
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Success ProbabilitiesProbabilities to meet approved project targets we call
Success Probabilities. These targets may be set for all project parameters that will be controlled (expenses, duration, material consumption).
Target dates do not belong to any schedule. Usually they are between most probable and pessimistic dates.
A set of target dates and costs for project phases (analogue of milestone schedule) is the real project baseline.
But baseline schedule does not exist!69
Performance Measurement problems
It means that application of usual project performance measurement techniques (like Earned Value Analysis) is complicated.
Without certain schedule and cost baselines it is impossible to calculate Planned and Earned Value.
If we select some schedule (Optimistic or Most Probable) as the project management baseline the values of Performance Indices that are lower than 1 do not mean that the performance is worse than expected.
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We recommend to use optimistic schedule for setting tasks for project work force and manage project reserves.
The schedule that is calculated backward from the target dates with most probable estimates of activity durations we call Critical schedule.
The difference between start and finish dates in current and critical schedules we call start and finish time buffers (contingency reserves).
The difference between activity (phase) cost that has required probability to be met and optimistic cost of the same activity (phase) we call cost buffer.
Buffers
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There are time, cost and material buffers that show contingency reserves not only for a project as a whole (analogue of Critical Chain project buffer) but also for any activity in the optimistic project schedule.
Sample Critical Schedule
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Let’s look at the difference between accuracy and precision.
Accuracy: Precision:
Monte Carlo and 3 Scenarios
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Monte Carlo means Accuracy but lack of Precision.3 Scenarios means Precision but lack of Accuracy.The choice depends on management approach.Our approach may be called “Management by
Trends”.We think that trends supply management with most
valuable information on project performance.We think that trend analysis helps to discover
performance problems ASAP and to apply corrective actions if necessary.
Monte Carlo and 3 Scenarios
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It is the main reason why 3 scenarios approach was selected.
We think that the quality of initial data for project risk simulation is never good enough but Monte Carlo risk simulation creates an impression of accuracy that is actually dangerous for project managers.
In any case we need Optimistic schedule and budget for project performance management.
We need to understand what happens with success probability during project performance and so we need data precision.
Monte Carlo and 3 Scenarios
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Performance measurement routine shall be set for all projects belonging to the program.
Program schedule is revised regularly. For most large programs it is done weekly. To be able to reschedule the program it is necessary that all projects belonging to the program have the same data date.
So the program management team requires from all project management teams to enter actual data of their projects at specified dates and time (for an example: each week on Tuesday before 12:00 the actual status on Tuesday 08:00 shall be entered).
Performance Measurement
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If different projects have different data dates then program scheduling became impossible and most reports will not be reliable.
So setting the rules for entering actual data is mandatory for program/portfolio management.
Program/Project planners shall keep performance archives to be able to get trends of program/projects parameters.
Performance Measurement
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We recommend to manage projects and programs basing on the analysis of performance trends.
If some project is 5 days ahead of the baseline but one week ago it was 8 days and one month ago 20 days then some corrective action shall be considered.
If the project is behind the schedule but the distance become smaller then project team improved project performance process and interference is not necessary.
Management by trends
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So trend analysis shows short term performance results and helps to make timely management decisions
Usually project management team analyses trends of main project parameters like duration, cost, profit
Negative trends require considering corrective actions.
Management by trends
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Earned Value Analysis is another method that is used for estimating program/project performance.
But this method shall be used very carefully and only in combination with other methods.
If program performance is estimated only by Earned Value reports it may create wrong motivation for project management teams.
Earned Value Analysis
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Let’s consider small sample project consisting of only three activities.
Resource A is overloaded.
Earned Value Analysis
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After project leveling we get the following schedule that has no resource conflicts and may be approved as the project baseline.
Earned Value Analysis
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If the team will start the performance with activity 3 the EV reports will be perfect until the last day when it will became clear that the project is late.
Earned Value Analysis
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Earned Value Analysis has certain weak points because: the real situation may be distorted,project managers are motivated to do expensive jobs
ASAP and cheap jobs ALAP,it does not consider if activities that were performed
were critical or not,it does not consider project risks,It is hard to interpret project performance results
when baseline schedule does not include contingency reserves.
Earned Value Analysis
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We consider success probability trends as the really integrated project performance measurement tool.
Success probabilities may change due to:Performance resultsScope changesCost changesRisk changesResource changes
Thus success probability trends reflect not only project performance results but also what is going on around the project.
Success Probability Trends
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Success probability is a measure of project buffer penetration.
If in the middle of the project half of project buffer was consumed it does not mean that the project is performed as expected.
If most risks were behind then success probability will become higher and it will tell us that project buffer consumption was lower than expected, if success probability went down then buffer consumption is too high and it is necessary to consider corrective actions.
Measurement of buffer penetration
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Success probability trends may be used as the only information about project performance at the top management level because this information is sufficient for performance estimation and decision making.
We call Management by Trends methodology SDPM.
Success Driven Project Management
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1. There is a need for common methodology, templates, reference-books to be able to implement EPC program project management system.
2. There is a need for Program Management Office – organizational unit that develops EPC program project management standards, collects actual information on project performance and works with the Program Schedule Model, creating and updating EPC program plan and analyzing program performance.
Success Driven Project Management Tips
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3. Most norms and standards are usually applied to the activity physical units (m, t, m3, piece, function point, etc.). So it is necessary to plan activity schedule and to monitor program performance basing on physical quantities (volumes of work) measurement.
4. Program schedule model includes the models of individual projects and shall be resource and cost loaded.
Success Driven Project Management
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5. We recommend to create a library of project fragments that may be used for fast development of the detailed project schedule models.
6. We recommend to set reliable target dates basing on risk analysis and simulation, but to use optimistic program schedule for setting tasks for project work force.
7. Time and Cost contingency buffer penetrations shall be regularly re-estimated. If these buffers are consumed too fast there is a need for corrective actions.
Success Driven Project Management
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8. We recommend to keep project archives and to analyze trends of project and program parameters.
9. If trends are negative corrective actions shall be considered even if the status is good.
10. Earned Value Analysis supplies management with the useful information on program status. But it shall be used carefully and only as the supplement to other methods of program performance measurement.
Success Driven Project Management
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11. Success Probability trends are the best integrated indicators of program health.
Positive trends show that recent program performance was better than expected. Negative trends show that buffers were consumed faster than expected and corrective actions may be necessary.
Success probability trends depend not only on program performance but also on risks that may change during program life cycle.
Success Probability Trends may be considered as integrated indicators necessary for proper decision making.
Success Driven Project Management
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Success Driven Project Management Flowchart
REFERENCE-BOOKS:
Resources
Materials
Cost Components
Cost Breakdown Structure
Resource Breakdown Structure
Calendars
Resource Productivities
Unit Costs
Material Requirements per Volume Unit
Skills
Multi-Resources
Code Structures Typical Fragnet LibraryProject
Schedule
Project Budget
Risk Register
Issue Register
Risk Analysis
Success and Failure Criteria
Success and Failure
Probabilities
WBS Templates
Performance Reports
Success Probability
Trends
Corrective Actions
Work Authorization
-
+
Project Portfolio
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Resource Critical Path is the same as Critical Chain except suggested approach to determining Critical Chain does not include taking into account supply and financial constraints.
The methods for Critical Chain calculation that were described are rather qualitative. I never met the clear description of CC calculation algorithms.
RCP and CC
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CCPM suggests to find Drum resource and create the schedule and determine Critical Chain scheduling activities of this Drum resource.
SDPM does not look for drum resource. At different project phases different resources may be critical, Resource Critical Path is calculated applying traditional resource levelling.
Drum Resource
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SDPM suggests to use Optimistic estimates for project stuff management.
CCPM suggests to use Most Probable estimates.
Using most probable estimates still means that there are some reserves for usual problems and these reserves will be lost in any case (Parkinson Law):
‘WORK EXPANDS SO AS TO FILL THE TIME AVAILABLE FOR ITS COMPLETION’
Optimistic or Most Probable?
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CCPM suggests to estimate excessive contingency reserves that people added to most probable activity duration estimates, take them away, summarize and put in a dummy activity that is called Project Buffer and follows the last activity of Critical Chain.
SDPM uses risk simulation for setting reliable targets and project time buffer is the difference between project schedule finish and target finish. Project time buffer does not belong to any chain.
Besides, SDPM also works with Project Cost Buffers and Material Buffers.
Project Buffer
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CCPM suggests to estimate excessive contingency reserves that people added to most probable activity duration estimates, take them away, summarize and put in a dummy activity that is called Project Buffer and follows the last activity of Critical Chain.
SDPM uses risk simulation for setting reliable targets and project time buffer is the difference between project schedule finish and target finish. Project time buffer does not belong to any chain.
Besides, SDPM also works with Project Cost Buffers and Material Buffers.
Project Buffer
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CCPM suggests to create feeding buffers on activities that precede Critical Chain activities to protect Critical Chain.
CCPM proposes that Critical Chain shall never change.
SDPM does not protect any chain – project schedule is regularly recalculated and risks analyzed.
Besides Resource Critical Paths in optimistic, most probable, and pessimistic schedules may be different.
Feeding Buffers
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CCPM suggests to pipeline projects in the portfolio (to perform them one after another) to avoid multitasking.
SDPM suggests almost the same – always apply priorities to the portfolio projects calculating portfolio schedule. But if resources are available they may be used on the projects with lower priorities without delaying prioritised project activities.
Besides there are special cases when multitasking is useful. An example is on the next slide.
Multitasking
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CCPM does not suggest reliable quantitative methods for analyzing buffer penetration. Dividing buffer into three zones (green, yellow, red) is one of them. Entering yellow zone means an alert, red requires corrective actions.
SDPM estimates buffer penetration by success probability trends. If the trend is negative then project buffer is consumed faster than expected.
If in the middle of the project performance project buffer is half consumed it may mean excellent performance if most risks are behind and poor performance if most risks are ahead.
Buffer Penetration Estimation
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