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Posted by on Nov 28, 2012

Scheduling: Planning to Get The Work Done – Part I

lady on a calendarRESOURCES

The sixth Principle of Project Management is, “You can do a lot, if you work out your schedule.” Scheduling is defined in the PMBOK® Guide under Project Time Management and entails 6 processes: Define Activities, Sequence Activities, Estimate Activity Resources, Estimate Activity Duration, Develop Schedule, and Control Schedule. Scheduling is a wonderful science with many helpful tools available for project managers to get it right. The science and math which make up those effective tools give us very linear and predictable results. Hurray for science and math!

In this blog, I want to concentrate on the Estimate Activity Resources process. I stated that scheduling is linear and predictable, but the instant we add humans we get non-linear behavior. The math and science do not always apply once we attach the human connection. Please don’t misinterpret, As a project manager, I need those humans. I can’t do it alone. Humans are good, reliable, sometimes experienced assets to the project. It’s just that we (I include myself as a human) don’t always adhere to the linear, mathematical model of the scheduling engine.


So we need Fred to accomplish a week long, 40-hour task. What are we assuming if we think that a 40-hour task is a week’s worth on calendar? We are assuming that Fred is dedicated only to the work on my project. How arrogant! Fred is probably assigned to several projects and is not fully dedicated to my project. When we assign humans to work, we must separate the effort (human energy required) from the duration (calendar consumed by the activity). Fred may need two weeks to complete the 40 hour task because he only has 4 hours a day to dedicate to my project. WARNING! Most scheduling engines will assume that every resource is 100% dedicated to the assigned task and humans don’t work that way. The scheduling engine will assume an overly optimistic schedule and we must correct its thinking, because humans require a bit of pessimism when work is the product.

In order for a schedule to be realistic we must consider the effort and duration required to accomplish a task. By assigning the resource to the task using the reality of how work will be accomplished by the human, we get closer to schedule reality. And we’re assuming that Fred’s availability is desirable. Remember, resource availability is not a skill. Just because Fred is available to perform the work, doesn’t mean Fred is the most desirable resource for the work.

The calendar also plays in the availability space. Did you consider holidays, vacations, and other time off sanctioned by the company? Schedule reality must consider the Paid Time Off opportunities.


Is Fred really good at this task or is he a junior resource for the work? Is there a mix of capabilities assigned to the task? Non-linear behavior will appear when there are multiple assignments with mixed capabilities. Fred may be the expert, but is not available. Two junior resources will probably not accomplish in 40-hours what one Fred could do. Also don’t forget the ramp up factor. Fred may be capable, but needs a learning curve to get better at the task. The schedule would need to reflect the ramp up time in order to be accurate. The opposite may be true is there is a learning curve in which repeated tasks can become shorter over time. If there is efficiency to the learning curve, the schedule may be shortened by this reality.


The skill or perceived skill of the human is also a factor. The best should be able to get the work done faster thus shortening the schedule, but that is not always true. Have you considered boredom, repetition, or the proximity to PTO as a variable to the schedule? Non-linear behavior lurks everywhere. REMEMBER: availability is not a skill! We do want the very best humans to perform the work for us, but we don’t always have the luxury of being able to select them.

All of these factors plus some I haven’t thought of yet will interact to cause the schedule to be unrealistic. Understand the difference between effort and duration, human availability, capability, and skills. My advice, be a little pessimistic when scheduling humans to get the work done. If we are talking about non human resources like a dump truck, well some of this blog is no longer true. Dump trucks don’t take holidays, but their drivers do.

This post is the first in a two-part series. To read part II, click Scheduling: Planning to Get Work Done – Part II.

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