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Author: Eric Uyttewaal

What Type of Schedules Should Program Managers Request?

Time Modeling is the simplest way of working with project scheduling applications (like Microsoft Project and Oracle Primavera) that everyone can learn in one or two days of training (‘introductory’ level).

The ‘intermediary’ level is modeling time and workloads (Workload Modeling), which requires you to learn many more features in your scheduling application and requires adding much more data to your schedule. After gaining experience with Time Modeling, Workload Modeling requires one or two additional days of training. The highest or ‘advanced’ level of proficiency with project scheduling applications is modeling the cost (Cost Modeling that includes time, workloads and cost) and keeping the intricate model of your project alive during the entire life of the project. This requires solid work experience with project scheduling applications, an additional few days of training, and, of course, executives that expect it to happen…

Proficiency Levels

Ever wondered what the commonly used terms ‘introductory’, ‘intermediate’ and ‘advanced’ mean in terms of Microsoft Project proficiency? Have you ever had to choose for your own professional development between an ‘introductory’, ‘intermediate’ or ‘advanced’ course in Microsoft Project? Were you forced to read the detailed course syllabus? In this article, we will propose a clearer way of describing the levels of proficiency for project scheduling in general, and Microsoft Project, in particular.

This article reflects some of the insights we gained from training 250 project managers at a large department in the Federal Government last year. These insights may help you strategize your own personal training or it may help a project management office purchase the right type of training for their community of schedulers, i.e. Microsoft Project users. Here is what we learned in 2016 during the delivery of twenty courses, each three days long, with about 12 project managers each, on average:

  • The early groups of students we trained were very keen to learn; they picked up concepts quickly and could handle a lot of content. We trained these project managers in most, if not all, features in Microsoft Project: modeling the time aspect of the project, modeling the workloads of the resources, and some groups even how to model costs with a dynamic schedule. 
    The later groups of students were slower leaners, were often cajoled by their managers to take the course: They were more intimidated by Microsoft Project and more easily overloaded with information. Some of these project managers were simply ‘not ready’ to load resources into their schedule. We found ourselves as trainers having to switch from ‘effort-based scheduling’ (labeled ‘workload modeling’ in this article from hereon) to a simpler form of scheduling: ‘duration-based scheduling’ (labeled ‘time modeling’ in this article) for these later groups. We made this switch out of necessity even though everyone really needed to know workload modeling because almost all their projects were software development projects.
  • All project managers were expected to report on cost in Excel every quarter in this federal department, even though these reports could more easily be created and maintained in Microsoft Project since the projects often shift in time. In Excel, each project manager had to provide a cash flow report on what they had spent and what funding they needed in the remaining quarters of their fiscal year. This caused a lot of work in Excel when delays happened or when new deliverables emerged. In other words, these reports required brain surgery in Excel every quarter. The cash-flow reports could much more easily be maintained in Microsoft Project, because it reschedules costs automatically when delays happen and adds cost when new deliverables are added while preserving the original cash-flow in the schedule baseline (that was approved for the project). Why did this organization not expect their project managers to use Microsoft Project instead of Excel to report on cost? The answer is: ‘modeling cost’ is the most advanced use of Microsoft Project and requires the highest level of proficiency with this application that was not present in this organization, or feasible through training in the time given.

As you know, there are ‘predictive’ versus ‘adaptive’ approaches to scheduling. The mainstream predictive approaches are: Critical Path, Resource-Critical Path, Critical Chain, Earned Value, whereas the adaptive approaches are: Agile, Scrum, SAFe. This text discusses mostly predictive scheduling, after all, you model time, workload or cost typically for forecasting purposes.

Model Time, Workloads and Cost

We would like to present the following operationalization for the vague terms ‘introductory’, ‘intermediate’ and ‘advanced’ proficiency levels of using Microsoft Project that, by themselves, do not mean anything except a hierarchical ranking between them:

  • Introductory: model Time only (‘Time Modeling’): You model the duration and finish date of the project in order to monitor if your project will finish on time. The time model allows you to view the most current duration of the project continuously and, therefore, control the duration of your project better. It increases your chances to finish the project on time.
  • Intermediate: model Time and Workload (from here on simply referred to as ‘Workload Modeling’): Portfolio and Resource managers may be asking you for the resource requirements for your project before approving your project, which requires modeling the workloads in Microsoft Project. Resource requirements are most often reported as number of Fulltime Equivalent Employees – FTE’s – by role by month. Once the project is approved, you need to model the total workload for each resource in detail for determining: If the workloads of all team members are reasonable and if they are evenly spread between them. In other words: If the project is feasible from a resourcing point of view.
  • Advanced: model Time, Workload an Cost (from here on simply referred to as ‘Cost Modeling’): you attempt to model the cost side of your project in order to monitor if you are staying within the project budget. The cost model allows you to control the expenses of your project better and increases your chances to keep the project within its budget. Earned Value Management (EVM) is an example of a specialized case of modeling cost: If you need to implement Earned Value, you will need advanced schedulers that know how to model cost in Microsoft Project. This may explain why many organizations struggle with making Earned Value really work even with the current drive of the US Government to implement it on major capital programs.

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There is hierarchy between the different types of modeling: if you want to model workloads, you will have to build a time model as well and, probably, first. If you want to build a cost model, you will have to build a workload model first (that needs a time model). You can see this hierarchy in the next illustration depicted as the steps of a staircase.

Progressive Elaboration

Uyttewaal 102317 aThere is also progressive elaboration to get from one level to the next level: With every step up, people will need to add more data to their schedule model. The illustration indicates what data needs to be added at each level. You can elaborate a time model and convert it into a workload model; we estimate that the amount of data is about 20 times the data in a Time Model; there are typically 7-9 activities per deliverable plus all resources plus assignments on each activity. If you spent some more time planning, a workload model can be transformed into a cost model; we estimate that the amount of data doubles going from a Workload Model to a Cost Model.

Tip► In summary: if you have a time model with 50 pieces of data entered (line items and fields), you will need to enter about 1,000 more pieces of data to get to a Workload Model and then another 1,000 pieces of data to get to the Cost Model, to a grand total of 2,000 pieces of data (which, by the way, is NOT the number of tasks; the number of tasks may only be 300 in this Cost Model). You can see the level of detail and the amount of data grow significantly when progressively elaborating your dynamic models from a Time Model, to a Workload Model and, finally, to a Cost Model. Therefore, you really need to ask yourself at the start of each project: What do I really need for this project: a Time Model, a Workload Model or a Cost Model?

Three Levels of Proficiency in Scheduling Projects

The illustration lists what data should be added at each level of progression:

  • In order to monitor if a project is on time, you need to capture at least:
    • Deliverables,
    • Duration estimates,
    • Dependencies between the deliverables
    • Deadline dates
      Do not enter Dates in Start or Finish fields, because this creates many date constraints and a rigid model. Notice all these words start with a ‘D’, so we normally refer to this with our mnemonic ‘4D 1D scheduling’.
  • In order to monitor workloads, you need to add to the time model the following:
    • Activities that will create each deliverable,
    • Activity Effort: Activity Effort is the effort estimate expressed in person hours that is needed for each activity, which is captured in the field ‘Work’ in Microsoft Project.
    • Availabilities: you need to enter all generic resource roles and/or actual resources (people of flesh and blood) and their availability to the organization (capacity),
    • Assignments: who will do what activity.
      All these terms start with an ‘A’, so we refer to ‘workload modeling’ also as ‘4A-scheduling’.
  • In order to monitor the cost of a project, you need to add more data to the workload model:
    • Capital Available: The capital available is the budget as approved,
    • Charge Accounts: Account categories from the budget in a lookup table visible in a custom field in Microsoft Project to tag tasks, resources or assignments with these charge accounts.
    • Cost and Material Resources: Cost resources and Material resources to capture all other expenses needed for the project.
    • Charge Rates: These are the Standard Rate, Overtime Rate and Cost per Use for each resource Many organizations use so-called blended rates that are average rates for each role, so HR does not need to reveal each person’s salary, information considered private.
    • Cost Accrual: Cost accrual is when the costs accrue (i.e. should be charged) to the project; the options are: At the Start or Finish of an assignment, or Prorated – spread out over the duration of the assignment.
    • Changing Rates over Time: How rates change each calendar year (a.k.a. rate escalation).
      All these terms start with a ‘C’, so we refer to ‘cost modeling’ also as ‘6C scheduling’.

As you add more data, the schedule model becomes more complex and will require more effort for keeping it up-to-date. As you can see, each next-level model needs the previous, simpler model(s) as a starting point, as input:

  • Before you can create a Workload Model, you need to have a complete Time Model.
  • Before you can create a Cost Model, you need to have a complete Workload Model (that needs a complete Time Model).

Tip► As you can see, there is natural progression between these different types of modeling while learning your scheduling application: We recommend that people start with modeling the time of their project first, then try to model workloads, and, eventually, round of their skillset with modeling costs.

Time Model Example

We will look at a house renovation project to illustrate each type of model. By the way, this is the project schedule I created for the renovation of my own home, so it is a real-world example.

The time model of this project looks like a Gantt Chart with all Deliverables, all Durations and all Dependencies; some of the deliverables have Deadlines but no Start or Finish Dates (4D 1D scheduling):

Uyttewaal 102317 b

As you can see, it is a small schedule, but all pertinent information is there for this 4D-1D time model. You can also see that this schedule is a very simple model of the project that can easily be explained to any stakeholder. Regardless of its simplicity, this schedule allows you to forecast the project:

  • Deliverables: All deliverables, the things of value to the client, are listed
  • Deadline: Deadlines are promised dates, or, in this project, the contractual dates between the owner of the house and the general contractor. The agreed-upon dates are entered for each deliverable as captured in the home renovation contract; they are entered into the Deadline date field.
  • Durations: The general contractor came back to me with durations estimates for each deliverable and I entered them into the time model.
  • Dependencies: The relationships between the deliverables are captured on a high-level: For example, we wanted the Water System and Septic System out of the way before the renovation of our home was started.

You can see that I used some tricks to make the Gantt Chart look nice:

  • I colored all milestone text (ribbon Format, button Text Styles) and all milestone diamonds (ribbon Format, button Bar Styles) red to make them stand out.
  • You can see that I created a new field called: Total Slack until Deadline: Microsoft Project does not calculate the Total Slack from the Deadline date back in the backward pass. Instead, it calculates from the Early Finish date of the project back. So, I added this custom field Text1 with the following formula to see how many days were left before the deadline as captured in the contract: 
    Note, the date #12/31/2149# is the end of the timescale in Project 2016 ; unless there is a valid Deadline date for the milestone, the formula will output nothing in this field. As you can see, there are only three milestones with a Deadline date entered. 
    It allowed me to see how many days are left until the contractual deadline dates, a very useful tool when working with general contractors (and any other vendors for that matter). It allowed me to regularly ask the question to the general contractor and his trades people: There are X days left for you to finish this task; will you make it within this timeframe?
  • I wanted to see that the amount of Total Slack until Deadline increases from the start of the project, via all milestones to the end of the project and you can see that it does go up from 10 to 50 days and then to 74 days. This is the hallmark of a healthy schedule. The further into the future, the larger your time buffer needs to be, so you can accommodate the unforeseens (‘known unknowns’ and ‘unknown unknowns’).

Workload Model Example

I have now taken the Time Model and added the 4A’s to it: Activities that create each deliverable, the Activity Effort (field ‘Work’ in Microsoft Project) for each activity, the Availabilities (all resources and their availabilities to the project, and Assignments of resources to activities. One of the main outputs of the Workload Model is a view that displays the aggregated workloads by resource in the project; you can then check if they are reasonable: i.e. if they fall within (reasonable boundaries of) the availability of the resources. We developed the following Resource Usage view with the field Work replaced with % Allocation (ribbon Format, button Add Details). You can see that the workloads are fairly reasonable: everybody is below 100% allocation, except for the Owner (me!) who has some overtime in March: 126% allocated:

Uyttewaal 102317 c

The model has expanded from 11 line items in the Time Model to 183 line items in this Workload Model; you can see that the amount of data exploded by a factor of almost 20 (!) and that it is a lot more challenging to create this workload model in the first place and that it requires a lot more effort maintaining it during the project execution phase that is always hectic. In the following screenshot, you can see a small part of the Gantt Chart of our Workload Model, i.e. the activities I performed to sort out the Water System deliverable:

Uyttewaal 102317 d

Here are some tricks I added to this Workload Model:

  • Notice that I carefully entered the Units for each assignment; there were many activities that take a lot of elapsed time (column Duration) but not much effort (column Work); for example, observe activity ‘3 Interview at least 3 water system vendors’; it takes 2 weeks to meet with three vendors and each meeting only takes about one hour, which leads to an assignment percentage of only 4%, or 0.04 in field Units (NEW). These are the details that you need to capture correctly in order to model workloads accurately.
  • Notice the number of resources assigned to each activity is expressed in terms of a Percentage, i.e. 4%. You can express it also in Decimals (e.g. 0.04) as set in the options: Ribbon File, item Options, tab Schedule, under Show Assignments Units as a.
  • Notice the field Units (NEW) that I inserted between the out-of-the-box fields Duration and Work. This is a custom-made field I published and recommended in my book Forecast Scheduling that always reflects the latest number of resource units (unlike the Units field in the Assign Resources dialog that since MS Project 2010 reflects the last, manually entered value). I used one of the extra fields in MS Project: The Number1 field (insert Number1, right-click on it and click Customize Fields, button Formula). Our customized Units (NEW) field has the following formula: 
    IIf([Resource Names]=””,”No Resources”,IIf([% Complete]=100,”Complete”,IIf([Remaining Duration]=0,0,CSng([Remaining Work]/[Remaining Duration]))))
    The essence of the formula is the last bit where [Remaining Work] is divided by [Remaining Duration] as per the formula hard-coded into MS Project that we discuss extensively in the Forecast Scheduling book: 
    Duration * Units = Work
    Units = Work / Duration. 

Cost Model Example

At this point, we take the Workload Model and we add the following 6 C’s: Capital Available (approved budget), Charge Accounts (expense categories), Cost and Material Resources, Charge Rates (Standard Rate, Overtime Rate and Cost per Use), Cost Accrual (Start, Finish or Prorated), and Changing Rates over Time. One of the main outputs of the Cost Model is an overview that shows if you are still within budget or if you are going over: We developed the following output based on the Task Usage view:

Uyttewaal 102317 e

Here are some tricks I applied to get to this representation of the cost of the project:

  • I sorted the Charge Accounts exactly the way I wanted by giving them numeric prefixes (1A, 1B, 2A, 2B, etc.) in the Value field. Note that MS Project in the Edit Lookup Table dialog, displays the Descriptions (if filled in) as the names of the group, but it sorts by its Values which is funny. In short, the numeric prefixes need to be entered into the Value field; you can leave the Descriptions field blank.
  • I renamed the Task Name column heading to Charge Accounts in the Field Settings dialog (right-click on column heading, click Field Settings)
  • Pay attention to the alignment of money amounts in the Field Settings dialog (right-click on column heading, click Field Settings); money should be right-aligned.
  • Get rid of the decimals in ribbon File, item Options, tab Display.

If you are not entirely happy with the way MS Project lays out the information, you can copy and paste into Excel and make it prettier. Copy first the Charge Accounts, then the numbers in the timescale:

Notice that the number of resources doubled (as shown in the following screenshot of part of the Resource Sheet) when adding the cost and material resources to the schedule. Renovation projects typically have many Material resources, whereas IT-projects have more Cost resources (goodwill, licenses, royalties, travel, facility rental, etc.):

Uyttewaal 102317 f

All these material resources were then assigned to the appropriate activities.

Here are the tricks I applied to create this view:

  • The Material Label field is important for Material resources, because their label shows up when you start assigning them to activities, for example, in the following way: 140 backsplash tiles [square feet] where tile is the resource Name and square feet is the Material Label.
  • Notice that you need to pay attention to the field Accrue At in renovation projects: Most vendors are paid at the End, whereas all materials are paid upfront (Start).
  • I sorted the resources as follows in ribbon View, button Sort: Sort by: Type,  Descending, Then by: Name,  Ascending and I used  Permanently renumber resources to get the list you see in the previous screenshot.

After entering all Cost and Material resources, they needed to be assigned in the exact quantities as per the architectural drawings:

Uyttewaal 102317 g

Benefits of the Time, Workload and Cost Model

The main benefits of each model are:

  • Time model: You will be able to tell if the project is on time at any time as long as you keep the lean-and-mean model up-to-date during project execution. Another benefit is that you will spend very little effort on scheduling the project as well as on maintaining the project schedule during the busy execution phase of the project.
  • Workload model: You will be able to tell if all workloads are within the availability of the respective resources. Also, you can spread the workloads evenly and tell if more projects can be authorized by portfolio managers. Meanwhile, you still have the Time Model as well (that is a subset of the Workload Model) and its benefits: You can tell if the project is on time.
  • Cost model: You will be able to tell if a project is still on budget. Meanwhile, you still have the Time Model and Workload Model as well and their benefits:
    • Time Model: You can tell if a project is on time.
    • Workload Model: You can tell if all workloads are within the availability of the resources and if the workloads are spread evenly.

Scheduling Maturity

The scheduling maturity of project managers in your organization determines which type of model you can request and expect from the project managers:

  • If the maturity is low, we recommend you aim for time modeling.
    If you have new project managers or ones new to scheduling, the scheduling maturity is likely low and we recommend you ask them to use the simplest way of scheduling: time modeling. We often introduced this as ‘duration-based scheduling’ to our client organization. 
  • If the maturity is medium (and the projects involve a lot of labor and resources), we recommend you aim for workload modeling. 
    If you have project managers who have created some schedules in Microsoft Project, their maturity may be medium and you could ask them to model the workloads in Microsoft Project (workload modeling) if its main benefit is of value to your organization. We often introduce this as ‘effort-based scheduling’ at our clients.
  • If the maturity is high (and your project managers have cost responsibility), we recommend you aim for cost modeling.

If your project managers have created many schedules in MS Project and have implemented the best practices of scheduling, they are mature schedulers and you could ask them to model the cost in Microsoft Project (cost modeling) if this provides additional benefits to your organization.

Uyttewaal 102317 hThe following illustration depicts these recommendations with green checkmarks in white cells. You can see that the chart also shows some question marks and red crosses. The question marks depict situations that can be remedied with training. The red crosses depict situations that are in our opinion:

  • Undesirable (top-left): If your organization needs simple time models, you should not hire highly-mature project managers, because this would be a waste of money on their high salaries.
  • Unattainable (bottom-right): If you have low scheduling maturity, you cannot expect your project managers to start building dynamic cost models of their projects.

However, the situation of your project might impose the type of scheduling that you will need. For example:

  • You may have low mature project managers, but a large program needs to be carried out by your organization (e.g. business transformation, upgrade of core business system, ERP-implementation). Such a large endeavor may require reporting on cost and, therefore, cost modeling in Microsoft Project for which you need highly mature project managers and program manager. You will need to pay special attention to closing the gap by: training your project managers, hiring new highly-mature project managers, or contracting vendors to attract highly mature project managers.
  • You work for an engineering firm that wins a contract with the US Government on a capital project, which means that you will have to implement some flavor of Earned Value scheduling depending on the contract value. Earned Value is an advanced cost modeling technique that requires a lot of scheduling discipline and, therefore, high maturity. In this situation, you will also experience a gap that you will need to close.


In summary, Time Modeling is the simplest way of working with Microsoft Project that everyone can learn in one or two days of training (introductory level). The next, intermediary level is modeling time and workloads (Workload Modeling), which requires you to learn many more features in Microsoft Project and adding a lot more data to your schedule. This requires two additional days of training after gaining work experience in Time Modeling. The highest or advanced level of scheduling with Microsoft Project is modeling time, workloads and cost of your project (Cost Modeling) and keeping this intricate model of your project alive during the entire life of the project. This requires solid work experience with Microsoft Project, another few days of training, and, of course … executives that expect it to happen.

What is a Project “Schedule”?

In the world of project management, project schedules can be characterized by their level of sophistication, by their intended usage, or by the nature of their content:

  • In terms of sophistication, project schedules range from the simplest (activity listing, timetable), to the more comprehensive (bar charts which converge action with time), to the most complex (network-based schedules, such as CPM, where activities are causally linked).
  • Project schedules can also be characterized by their intended uses.  Early-phase schedules (more commonly called plans) can be helpful in forging a project execution strategy.  Examples of strategic plans include feasibility plans, optimization plan, and consensus plans.  Project schedules enjoy their greatest use as tools of communication, coordination, and collaboration.  In all cases, project schedules (including precursor plans) are tools of the project manager, intended to optimize their efforts to effectively manage the project.
  • The third categorization of project schedules relates to content of the presentation of the schedule. This content is conveyed using adjectives placed before the word “schedule”. Examples are “bar chart schedule”, “milestone schedule”, “submittal schedules”, “design schedules”, “outage schedules”.

What all project schedules have in common is an underlying assumption and belief: the project schedule models reality, whether that reality is anticipated or already realized.  No rational member of the project team would ever construe the schedule as the actual reality – only as a representation of a possible future reality.  A project schedule is not unlike a road map.  No one would attempt to drive on the map rather than in the streets.

The comparison of a roadmap to a project schedule is ideal for advancing the main point of this Open Letter: the project schedule models reality; it is not reality.  The project execution itself (as performed on the project) is the reality; the project schedule is the model used to manage that reality.  The correlation does not stop with the name of the model, the project schedule.  It goes deeper, in that for every entity on the project, there is a corresponding entity in the schedule:

  • Out on the project, there are actions; in the schedule there are activities. 
  • Out on the project, those actions consume time; in the schedule, activities have durations
  • Out on the projects, human performers interact with one another; in the schedule, activities are related through dependencies

The project schedule is an intricate, computer-based model of the reality (actual or future) of the project.

The project schedule models project execution.  As such, it is a “project model.` It does not model itself; it does not model the schedule. Therefore, it is not a ‘schedule model.’ `.

CALL TO ACTION: The above point of view may seem obvious to most people familiar with Project Management and Time Management. But the idea that the project schedule models the project execution does have its detractors , because the term `schedule model` has invaded the very epicenter of project management culture and thought, the PMBOK Guide in its 4th edition published in 2008. It invaded the PMBOK after the term was first inserted in the first edition of the Practice Standard for Scheduling that was released in 2007. The term “schedule model“ is not defined in the exposure draft of the Practice Standard for Scheduling (2nd edition) but described as “This schedule model integrates and logically organizes various project components, such as activities and relationships to enhance the likelihood of successful project completion”.

From our vantage point, the authors of this open letter recognize two distinct schools of thought, that sadly seem at polar opposites of one another.  There is what respectfully might be called the New School of Thought, and that therefore leaves the other to be called the Old School of Thought. 

The following table compares the two Schools of Thought. To be sure, the two perspectives differ on many important points, including terms, concepts, processes, objectives, and so forth.  To illustrate the wide chasm that separates these two opposite viewpoints, we have chosen just one term: the one meant to represent the project schedule.  The Old School thinks of the project schedule as a project model. The New School thinks of it as a schedule model. And this standoff is at the root of this Open Letter!

We ask you, our fellow Scheduling Practitioner: Which is the better choice of term?  The answer may be apparent from a common-sense review of the arguments on behalf of each. But, frankly, the authors of this Open Letter have joined forces because we so strongly believe that the most important opinion is the one coming from our primary customer, the project sponsor, and also from the intuitive understanding of the terms by the other stakeholders of the project, in particular the project resources. 

We must thus ask: What does the typical project manager consider the project schedule to be?  A project model or a schedule model?

There are two schools of thought on what a “schedule” is:

Old School of Thought

New School of Thought

A schedule is a model of the project.

Eric Uyttewaal defines “schedule” in the context of project management (“project schedule”) as follows in his book “Forecast Scheduling with Microsoft Project 2010” (
A schedule is a model of the project to forecast it.

Murray Woolf defines “schedule” in the context of project management (“project schedule”) as follows in his book “Faster Construction Projects” (
A schedule is a project execution model.

The term “schedule” is neither used, nor defined in the PMBOK (4th edition) and Practice Standard for Scheduling (1st Edition). Replacing this term is a new term, “Schedule Model”, which by its wording gives the impression that the schedule is the matter being modeled.

Both authors treat the project schedule as the model of the project: The schedule essentially IS the model.

Instead a new term was introduced and adopted in these standards which is: “Schedule Model”.

We do not need a new term because this definition embraces the way people commonly understand what a schedule is. (See explanation below this table.)

The new term “Schedule Model” was invented because the common meaning of the term “Schedule” was found to be not useful for professional schedulers.

This is at the heart of our overarching message; that the scheduling community has come up with a new term at the disregard of:

  • Our primary customer, the project sponsor, that uses the term “schedule“
  • The intuitive understanding of the term “schedule“ by all other stakeholders in projects

In keeping with the notion that the project schedule models the project execution, we are most comfortable with how the typical project sponsor views the project itself.  As we discern, they seem to see project execution as the purposeful orchestration of effort by numerous parties, and toward the production of a final single product, which is most often comprised of numerous sub-products, called deliverables.  As such, a project involves actions taken to produce those deliverables.

Project sponsors and most people understand the term “project schedule”: a schedule is a list of things created in the project and their due dates. Essentially most people think of a project schedule typically as being like this:

Project Schedule


Project Deliverables

Due Date

Requirements document

Aug 12 ’11

New Location

Aug 30 ’11

Remodeling Contract

Sep 14 ’11

Remodeled New Location

Nov 10 ’11

Move to New Location

Nov 22 ’11

If you look at the Old School definition (Schedule is a model of the project.), then you can see that this common understanding of a “schedule” is embraced by their definition. It is embraced because the example of a typical project schedule as shown above is the simplest model possible of a project.

Now, as it happens, scheduling practitioners tend to add “sophistication” to this simple model by:

  • Elaborating it into a more detailed Work Breakdown Structure (WBS) of phases, deliverables and often even activities and milestones.
  • Adding dependencies between the WBS-elements (network logic),
  • Adding duration and/or effort estimates to the model
  • Adding constraint dates and other constraints to the model
  • Adding resources and availability constraints to the model
  • Assigning the resources to the activities and checking on if the aggregated workloads of the resources stay within their availability constraints.

None of the enhancements, however, take away from the project schedule’s ultimate purpose, that being to model the project. The obvious value in embracing the Old School (which is also the common) understanding of the term schedule is that no new term (such as “schedule model”) is needed.

What has worked so well for five decades requires no improvement.  If we wish to put an adjective in front of the single word, schedule, then let it be the word “project” as in “project schedule”.  And if we wish to have a pronoun which reminds us that the project schedule is meant to model, then let it be “project model”, not “schedule model”.

CALL TO ACTION: Currently, the working group that will decide about which term will be adopted in the second edition of the Practice Standard for Scheduling (PSS) will deliberate on this issue in the last weeks of January of 2011. Inasmuch as this working group essentially “owns” the definition of the term “Schedule,” it has the power and influence to change it. If the PSS working group changes the term, the next edition of the PMBOK (the 5th edition) will likely reflect it.

So, the main question is: Should PMI re-institute the decades old understanding that a project schedule IS the model (of the project), or should it continue to argue its current line of thought, which is that a schedule is NOT a model and (thus) that we now need this new (technical) term “schedule model?” What is your opinion?

This Open Letter to the scheduling community asks you to: register your voice as to which school of thought you subscribe to! You can express your preference by writing an email to the project manager of the PSS Working Group of the 2nd edition of the Practice Standard of Scheduling, attention of Mike Mosley through the secretary of the working group [email protected]. We would appreciate you also copying one or both of the authors of this Open Letter as well, see their email addresses below. Please use the subject line “Schedule or Schedule Model“.

The window of opportunity to make a difference is closing quickly. You need to register your position before January 21 when their deliberations begin.

With sincere and deep concern for the future of the scheduling practice, we remain …

Eric Uyttewaal, [email protected]

Murray Woolf, [email protected]

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Eric Uyttewaal is one of the foremost authors/trainers/consultants on scheduling and on the use of project management tools from Microsoft. He authored the bestselling book “Dynamic Scheduling with Microsoft Office Project 2003” and his latest book is “Forecast Scheduling with Microsoft Project 2010”. Eric is founder and president of ProjectPro Corp, a company specializing in Microsoft Project and Project Server ( Eric has been involved in the Canadian Forces Supply System Upgrade Program, the Cognos (IBM) BI Suite release program and a Northrop Grumman Airplane Upgrade program. View Eric’s book “Forecast Scheduling”:

In 2010, Eric was named most valuable professional in project management applications “MVP Project” by Microsoft. In 2009, Eric received an award from PMI for his “Significant Contribution to the Scheduling Profession”. In 1997, he was President of the Ottawa Chapter of PMI, currently serving over 1900 members. From 2001 until 2004 and again since 2009, he is president of the MPUG-Ottawa chapter.

Murray Woolf is the president of The International Center for Scheduling (  ) and author of Faster Construction Projects with CPM Scheduling ( ).