9. How long will the work take?
When you start a project, stakeholders are usually interested in just two things: How much will this project cost, and when can you have it done? So how long will the project take? is really looking at estimating the project duration, and this is a project management process. The level of detail that you have available leads to the accuracy of your estimate. So more information leads to more accurate duration estimates you’ll need.
The activity list, which we call the activity list, is based on the work breakdown structure. So right there, if we don’t have the WBS and just have a general sense of the work, it’s going to be pretty tough. to create an accurate duration estimate. You also need to know the resource requirements—what resources do you need and when will those be available? Are there any special characteristics to the activities? For example, do you have to wait for things to cure or set up, or what are your resource capabilities? You think about your equipment as well as your people, and then do you have any historical information?
So things like organizational process assets will help you predict the key items that will help you estimate the project’s activity duration. Now, this is a project management activity. So we have inputs, tools, and techniques, and we have outputs. The inputs you’ll need are the schedule management plan, activity list, and activity attributes, resource requirements and calendars, project scope, statement, risk register, resource breakdown, structure, and enterprise environmental factors in the organizational process, assets, tools, and techniques.
Here, we have expert judgment, analogous estimating, parametric estimating, and three-point estimating. And we’ll get to those in a minute. And then group decision-making techniques and reserve analysis Just two outputs here: activity duration estimates and project document updates. Analogous estimating is a technique for estimating time or cost. An analogous estimate creates an analogy between similar projects. Now that’s a key thing here. It has to be similar work. So if you’re doing an IT project, the first one was to create a new network, and the second one is to create a new network but it’s slightly larger. That’s a good analogy. But if the second project is to install an SQL Server, those really don’t mesh together, so it wouldn’t be a good example of an analogous estimate. Now, in order to do an analogous estimate, you have to have historical information.
There has to be something to base the analogy on. Now an analogous estimate is called top-down estimating because you’re starting at the top of the project. They’re just making a comparison, and this is really fast and often unreliable. Parametric estimating is where I have a parameter such as “it will take 1 hour per unit to install.” It’s usually good for repetitive work. So things that you do repeatedly, like installing a thousand of these units. One thing this approach does not take into consideration is the learning curve. The learning curve is that the more often I do an activity, the better I become at that activity, and the faster I can become at that activity. So parametric estimating doesn’t consider the learning curve often because we don’t know what that learning curve may be. So periodically, especially on longer projects, we may have to come back and reestimate because we’ve become more efficient.
Three-point estimates are really an average where we have the optimistic, the most likely, and the pessimistic. It’s also called triangular distribution. So with these three-point estimates, you would take an optimistic estimate for each activity plus the most likely plus the pessimistic estimate divided by three. So all you’re doing is averaging, but you have to do it for each activity. Now, in this example, we could say the optimistic figure is 25 hours plus 45 hours plus 75 hours divided by three. We would predict that task to take 48.33 hours, according to current estimates. Use the programmer evaluation and review technique. It’s also called a beta distribution. It’s very similar to our three-point estimate.
This formula, though, is weighted towards the most likely scenario: optimistic plus four times the most likely plus pessimistic divided by six. So for example, in the same case, 25 plus four times 45 plus 75 divided by six With this, we would say it’s 46.66 hours. That’s what our prediction would be. Now, reserve time is where we take a percentage of our project and set it aside for cost overruns. Reserve time, however, like all of project management, can succumb to Parkinson’s Law. Parkinson’s Law states that work will expand to fill the time allotted to it. So in other words, if I say this activity will take 40 hours, and maybe in my mind I’m saying, “Well, it’s probably only going to take 30 hours, but I’m going to give myself 10 hours just in case anything goes wrong, it will magically take 40 hours.” That’s Parkinson’s law. It’s like the day before you go on vacation, you can get a ton of work done because you have to, but the day you come back from vacation, it takes all day just to do one email. Parkinson’s Law work will expand to fill the time allotted to it.
10. Developing the Project Schedule
Now that we know what activities require what particular resources, we’re able to start developing the project schedule. And it is here that we actually decide when the work will be done. So with this task, what we’re looking at is the sequence of events. This is putting the activities in the order in which they should happen. Then we look at how long the activities will last and when the resources will be available in relation to when we need them on the project. And this is also an activity where we’ll describe the relationship between activities. Now, in the process of developing a schedule, we have a lot of inputs to consider and must use a lot of tools and techniques. And this also creates a lot of output. So our inputs here are the schedule management plan, the activity list, activity attributes, and project schedule network diagrams.
We’ll look at that in a moment. Activity resource requirements, resource calendars, activity duration estimates, project scope statement, risk register, project staff assignments, resource breakdown structure, enterprise environmental factors, organizational process assets Now the tools and techniques schedule network Analysis—critical path method, critical chain method, resource optimization techniques, modelling techniques—leads and lags schedule compression scheduling tool. Now, those tools and techniques will create the schedule baseline, project schedule scheduled data, project calendars, project management plan, and project document updates. So that’s the entire process here for the tools and techniques to create those outputs. Now, project constraints—remember, a constraint is anything that limits your options. So I like to use the example of some very particular constraints with road construction. So I know we all love road construction. Imagine that there is a street project in front of your house, and this particular project has a start date of August 1, so it must start on August 1.
The reverse of that is that you have a finish date that says it must finish on August 31. So you have two types of constraints there. These are very restrictive. It has to start on a particular day or finish on a particular day. So you might have a consultant that’s going to come in on August 15, so that’s the only day that consultants are available. So it must start on August 15, or you have a trade show. And so your project must finish on December 12 because that is the day of the trade show. Other more forgiving constraints include the requirement to begin no earlier than August 1, so that road project in front of your house cannot begin before August 1. So it’s going to start by August 1 at the earliest, but it could start on the second, the third, the eighth, or have you. But it can’t start any time before August 1. More likely, that road project is going to start no later than a particular date. So you can start any time, but you can start no later than August 15. So start no later than a particular day. Then we have the inverse finish: we want that activity to run all the way through and finish no earlier than October 2 or, more likely, a deadline finish no later than October 2. Now, we may have some assumptions to deal with.
Now, assumptions in the schedule are where we have things like new work that’s come about because of a change or a risk that you assume isn’t going to happen or force major acts of God where you assume there’s not going to be an asteroid that lands in the middle of your project’s labor. You make the assumption that labour is going to be available through effort. You assume that people are going to work efficiently and accurately on your project. We also may have a risk. We’ve not talked a lot about risk yet. In our projects, risk is an uncertain event or condition that can have a positive or negative effect on the project. Now, risk may also be called a known or an unknown. A known risk is something that you’ve identified and done. An unknown risk is one that you did not anticipate or consider, but it entered your project and had an impact. Risk analysis does affect completion because it often takes time to study the risk event to see what effect thatrisk will have on the remainder of the project.
Risk affects cost, but it also affects time. And in a future session, we’ll really dive into risk. It’s an important topic for your exam. Now, all of this information has been set up for this particular slide. This is a project network diagram. This is called “activity on the node,” and it’s also known as a precedence diagramming method. Each one of these nodes, ABCD, and so on, represents an activity. The green line between the nodes represents the flow of activities. So in order to get to activity E, you have to first go through activity A to get to B, and then you can go on to D. And then when D is done, activity E can start to get the G, so we have to continue on. But notice that G cannot begin until Eis is done and F is done. And so this is the idea of a predecessor in succession, like we talked about a little bit earlier. We’ll take a closer look at the upcoming project network diagrams. But this just shows the flow of activities. This is the result of sequencing. You’ve put these tasks in this particular order to reach the end of your project.
11. Examining a project network diagram
Managing the critical path This is a topic that I get emails and questions about all the time. Well, first let me just address the critical path, which is the longest path in a project network diagram to reach each project’s completion. The critical path means that no activities on the critical path can be delayed. If you delay any activity on the critical path, your project is going to be late. So in this lecture, I want to walk you through the concept of the critical path and then how to calculate project float. Float means there’s an opportunity to delay an activity.
And there are actually three different types of float. We have free float, which means an individual activity can be delayed without delaying the early start of the successor activity. So, for example, I can postpone painting by two days without affecting carpet installation. Carpet won’t be here until day seven, so I have to finish by day five with the painting activity. That is called free float. One activity can be delayed without delaying the early start of its successor activity. Total float means an activity can be delayed without delaying project completion. So total float means that if I postpone this task, what effect will it have on the project’s completion? Project float means the entire project can be delayed as long as I don’t pass the deadline for the project. So, for example, this project is low priority and is going to take 90 days to complete, but we don’t have to get it done until December 31.
So here we are in February, and I have all the way until December to finish it. So I have a whole lot of project float because I have a very big window to get the entire project done. Now, on your exam, you might have two or three questions about float. Float, on the other hand, is only available on activities that are not on the critical path. So I’m going to walk us through the idea of how to find float. How can you determine what activities can be delayed and what activities cannot? How we do that is through a process called the “forward path.” Now, before we begin the forward path, it’s a really good idea to identify the critical path. So let me show you how you do that. In this particular project’s network diagram, we have two paths to completion. A to B to D, D to E, and E to G, and we have A to C, C to F, and F to G. Those are our two paths to the end of the project. Well, above each node, we have a number that represents the duration. If we add these numbers up, ABDEG So we have three, and two equals five, plus five equals ten, plus six equals 16, and two more equals 18. On path acfg, if we do the same thing, three and four are seven, four is eleven, and two is 13. The critical path is the longest path to completion.
So we know the critical path is up here, at ABDEG 18 days. All right, so we have that to work with to begin. Now, what that allows us to do is first examine what activities are on the critical path. Remember, the critical path has no float. Well, the noncritical path does have float. So what we have to do is complete a forward pass. a forward pass. We’re looking for the earliest an activity can begin and the earliest that an activity may finish. So you can begin activity A on Monday, day one. There’s no such thing as “day zero.” So you start on Monday, day one. And the earliest I can finish activity A is day three. So activity A, the early start, is one, and then the early finish is three. Now, why three? Why not four? Well, I begin on Monday, I work all day Monday, I work all day Tuesday, and I work all day Wednesday on activity A; that’s three days of duration. So that tells me the earliest I can finish is day three; that’s the early finish.
Now, for activities B and C, when do you think I could begin? What are B and C? If you said four, you’re correct. I work Monday, Tuesday, and Wednesday. On activity A, I go home, get into bed, and come back to work tomorrow. And now it’s day four, and my team can start activity B, and they can start activity C the next day, day four. So in order to find the next day, I just added one here. I’m just going from three to four. Now, in this example, activity B can start as soon as activity A is done, and activity C can start as soon as activity A is done. So that’s what we have here—that we have four and four. What is the earliest date I can complete Activity B? If you said day five, you’re correct. The reason why is that I’m working here on Thursday. So Thursday is day four; I work all day Thursday and all day Friday. And so that takes me to day five. There’s a formula I can use. The early start plus the duration minus one equals the early finish. And so that formula tells me what the earliest I could get to the early finish is. So let’s take a look at that. So four plus two is six. Early start plus duration is six, minus one is day five; the early finish for activity C, four and four, is eight, minus one is day seven. Now. When can I start my activity? D as soon as B is done. Or the next day, which will be day six. Six plus five equals eleven; minus one equals ten.
And when can I start? Activity F Well, the next day, which is day eight, plus four is twelve, minus one is eleven. Activity E: I can start activity E right after day nine or day ten. So my early start for E is 1111, and six is 17, minus one is 16. Activity G cannot start until both E and F are done. So the earliest I can begin G is day 1717, and two minus one equals 18. Now, here’s a little trick. The final day of your project should be the same length as the first, 18 days. So that is a way to check if you’ve done your math correctly. So this is day 18, and that activity G can be finished. It’s also the sum of our critical path duration, and that’s the forward pass. Now the backward pass is very similar, but I’m going to look for the latest day I can finish and the latest day I can start each activity. Now, what we’re seeing on our screen now—abde and G—that is the critical path. So I’ve highlighted those in pink because I know on the critical path there can be zero float.
Now, to find the late finish, I start at the end of the project because the latest I can finish this project is day 18. Then I use the formula here: it’s late finish (18), minus two is 16, plus one is 17, and that’s the latest I can start in activity G without my project being late. Now, you probably noticed something here that’s a little unusual. The earliest I can finish is day 18, and the latest I can finish is day 18. On the critical path, these numbers for the late finish and the early finish will be the same. The early start and the late start will be the same. That’s going to happen for each one of these nodes that we see in pink. So you can see on Activity E that the latest I can finish is Day 16. Well, how did I come up with 16? Well, I have to finish by day 16 because it’s one day prior to the latest that I can start activity G at day 17. On activity D, the latest I can start is E, which is eleven. As a result, the latest I can finish D is ten. And you can see that these numbers are starting to match up. Let’s look at activity D. We’ll just plug our formula in. For example, our late finish is day 1010, minus five is five, plus one is six. So it’s very similar to our forward pass. We’re just starting at the end and adding that one instead of subtracting the one.Activity B, the latest I can finish it is day five, and the latest I can start Activity B is day four, and then you can see Activity A. I go one day prior; three is the latest I can finish. Three minus three is zero.
There’s no such thing as day zero, and that’s why we add one back in. So three minus three is zero, plus one is one. Now on the critical path, a little shortcut Once you know your critical path and you’ve done the forward pass on the backward path, you can just drop those numbers down; they’re going to be identical. On the backward paths, there is no float on the critical path. So a little hint there if you’re intuitive; I’ll explain it in a second if you didn’t get it. Now look at activities C and F. C and F are not on the critical path, so there is an opportunity to delay. Let’s look and see what the latest I can finish activity F is. I can finish activity F no later than one day before activity G begins. So that would be Day 1616. Minus four is twelve, plus one is 13. The latest I can complete activity C is one day before the latest I can begin F. So, of course, that would be day twelve, minus four is eight, plus one is nine, and that is the forward pass.
I’m sorry; obviously, it’s not the forward pass; that’s the backwards pass because we started at the end and worked our way backwards. Now the difference between my late finish and my early finish will reveal the float available for that activity. So twelve minus seven is five. Now, if you prefer, you can go over and say, “Well, what’s the latest I can start and the earliest I can start?” and find the difference there. Nine minus four is five. I always go with the late finish and the early finish, but it won’t matter which side you use. In fact, it’s a good way to check your math. That number should be the same as in this example: nine minus four is five, and twelve minus seven is five. So there you go. So we’ll stick with the late finish. Now, on activity F, 16 minus eleven is five, and 13 minus eight is five. So what we know here on Activity C is that we can delay it up to five days without affecting the project end date.
12. Managing the schedule
Managing the schedule There are some things that you have to consider when it comes to managing the schedule. So I’d like to show you a few quick things here that will help you be a better project scheduler. First off, there is the concept of resource levelling heuristics.
Now, a heuristic is just a general rule that you should follow. A good example of a heuristic for scheduling is 40 hours a week. So on your project, you may say no one can work more than 40 hours a week. But if you’ve already scheduled people to work more than 40 hours a week, then you’ve broken that heuristic. Resource levelling limits the amount of available labour in a given time period. So in this example, this is one week in our project, and we have several resources that are scheduled for more than 40 hours a week. Well, we would have to flatten the schedule. So resource levels and heuristics would say that all of these people who have more than 40 hours are capped.
So we would have to limit the number of hours they could contribute to the project this week, and then they would have to start those again next week. That may be the same amount of labour overall on your project, but the duration of your project is likely to extend because they’re taking those hours that they can’t contribute this week and applying them next and next and so on. So it often extends the project schedule. Now, in the last lecture, we looked at the critical path method. There is another approach you can take that uses the critical chain method. The critical chain methodology of project scheduling focuses first on the delivery date. It focuses, second, on the availability of resources, something we don’t do in the critical path method that we looked at a moment ago. Consider if we have Bob on activity A and, let’s say, activity C at the same time.
Well, Bob can’t be in two places at once. So the critical chain would say, “Well, we have a conflict because Bob isn’t available in both.” Now, what the critical chain method does instead of float is add a buffer of time on each path, and it adds a buffer of time at the end of the project. So rather than putting float on each activity, it has a buffer that’s really like the sum of all available float for a path. And if any activity is late, it takes it out of that buffer. Buffers that are not on the critical path, that are not on the path that cannot be delayed, are called feeding buffers because those paths feed into the path that cannot be delayed. If you have a buffer at the end of the project, it’s called a project buffer.
The critical path doesn’t consider whether resources are available. The critical chain method does. You might have one question about the critical chain method. Finally, a few words about the schedule. compression If you’re done with your schedule network diagrams and you say, “Well, we’re not going to get done by our deadline,” we can compress the schedule through two different methods. Crashing is when you add people to reduce the overall duration. So this is only for activities that are effort-driven. So crashing adds people, but when you add people, you have to pay for them, so that can increase the cost. Fast tracking allows activities or even phases to overlap.
This happens a lot in construction, where part of the building may already be built, but the foundation is just being laid on the other side of the ground. As a result, those phases are chasing or overlapping one another. However, when you do fast tracking, you will be adding risk because if anything is wrong with the prior activities or phases, that affects the work that you’ve already done based on those prior activities or phases. Now, Monte Carlo simulation—it’s called Monte Carlo because it is named after Monte Carlo, the famous gambling mecca—looks at every possible combination of events. So usually what you do is you say “most likely,” “pessimistic,” and “optimistic,” and you say, “If any of these activities come in early, what will that do to the rest of my project?” Or you can go through and kind of cherry-pick. You could say, “If these activities are early, and these are on time, and these are late, what does that do to my project?” So it’s a piece of software that allows you to run what-if scenarios to predict project duration.
13. Schedule compression
How often will we tell stakeholders how long the project will take to complete? They come back with another question, and that question is, “Can’t you get this thing done faster?” Well, sometimes we can, and sometimes we cannot. It just depends on the conditions of the project. We do have two choices for schedule compression, and they come at a cost. The first choice is to crash the project. Crashing the project adds labor to it.
Crashing can and frequently does increase costs. Crashing, on the other hand, will only work on activities that require effort. So activities that allow us to add more and more labor will allow us to complete them faster. But recall those activities that have a fixed duration. Crashing doesn’t work. Now, one thing that’s interesting here when we talk about crashes is that we can use some logic here and say that if I have two people and it takes 80 hours of duration, can I add two more people? So I have four people total, and I can get it done in 40 hours of duration? Well, sometimes I can. Sometimes that will work, and sometimes it won’t. However, there is something we have to consider, and that is the law of diminishing returns.
The law of diminishing returns basically says that we cannot exponentially add labour to reduce duration. In other words, I simply cannot handle adding more and more people in order to complete everything in ten minutes. That just isn’t feasible. It just won’t work. So when we talk about the law of diminishing returns, the first thing we have to consider is the work. Can we add people to get the task done faster? The yield, though, remains constant. And the value of the work that we’re doing is the yield. So, for example, let’s say that we have an activity for which our profit will be $5,000. That’s its value. If we add 40 people to that activity, 40 would be a lot. If we add four people to the activity and our duration is reduced to 40 hours, that task is still only worth $5,000. If we had eight people, could we get it done in 20 hours? That task is still worth $5,000, and so on. So the law of diminishing returns says the value may be the same, but our cost for this added labour may increase and increase and increase.
The only time this method is really good to use—and there are many times when it is really good to use to add more people to a project—is when there is a bonus. So this is where I’m using the risk response to enhance the fact that I’m adding more people to enhance the positive opportunity of receiving a bonus, so the value goes up because I’m getting a bonus. If that value remains the same, I’m actually costing myself money because I have to pay for more and more labor. So the law of diminishing returns is something we have to take into consideration when crashing. Fast tracking is also a type of schedule compression technique. And fast tracking is when we allow phases and activities to overlap.
So phase one would be complete, and then phase two would start. Fast tracking would allow these phases to overlap. The trouble with fast tracking is that if anything goes wrong with the end result of phase one, it could affect phase two. So we may have to undo work in phase two to fix whatever was coming out of phase one. So, for example, in construction, if you’re constructing a really big building, you might allow phase two to begin before the foundation is set. So there’s some risk with doing that. So fast-tracking is introduced as a risk.
14. Controllng the Project Schedule
As a project manager, you want to control the project schedule. You want to keep delays out of the project; you want to keep the project work moving along. This process is really about adherence to the project schedule baseline. Now the schedule baseline is the prediction of how long the project should take. And then as we begin to stray away, if we have delays, our baseline shows what we should do, and the variance shows what we actually ended up with. So controlling the schedule is all about adhering to that baseline.
So to control the schedule, we utilise the schedule change control system, which is part of the project’s integrated change control. and we’ll look at that in detail in a future session. Controlling the schedule is also about measuring project performance. It’s understanding why variances have happened in the schedule so we don’t repeat that mistake. And then we may have to update the schedule. You may have to take some corrective action to get the schedule back on the baseline.And then, of course, you are documenting your lessons learned as you move through the project inputs, tools, and techniques, as well as the outputs for controlling the schedule.
My inputs I need the project management plan, the project schedule, work performance data, project calendars, schedule data, organisational process assets, and the tools and techniques that I’ll use. Performance reviews. How well are we doing on the project? I’m probably going to use some software here, like Microsoft project resource optimization techniques, modelling techniques, leads and lags, schedule compression, and some type of scheduling tool outputs. I get work performance information and facts about how we’re doing in the project scheduling forecast. Are we going to hit our milestones? Are we going to hit our deadlines? You may have some change requests, and then you may have to update your project management plan, your project documents, and organisational process assets. One of the keys to controlling the schedule is measuring project performance.
It’s where we tie a value to the work that we’ve done. And this is setting us up for earned value management, which we’re going to see in the next session’s cost. But what we’re doing is assigning a value to the work that we’ve done. We’re assigning a value to the work that we should have completed by this point in time. So those two concepts are called “earned value” and “planned value.” These enable us to predict how much more money we will require to complete the project estimate, as well as what our total will be at the end of the project. We also look for milestones, delivery dates, and key deliverables, as well as any deadlines associated with those. You may have to do some performance reviews like trend analysis, critical path analysis, the critical chain method, earned value management, and scheduling forecasting. All of these allow you to look at the delays and the various experiences and see how well your project and project team are performing. You can use all of these as well when you’re dealing with vendors. How well is the vendor performing?
15. Section wrap
Hello again, and welcome to the end of this section on project time management. We talked about a lot of things in this section. Remember that project time management refers to the time between project initiation and project closure? So that time is our schedule. So whenever we have to define our schedule, we first have to take our project scope, and that’s decomposed through the work breakdown structure all the way down to work packages.
And the smallest item, the work package, correlates to an activity in the activity list. So we define our activities. Once we have our activities defined, we can begin examining what types of resources we will need in order to complete these activities. So based on what resources? We have a senior engineer versus a junior engineer, a really powerful piece of equipment versus a smaller piece of equipment that can affect the duration of each activity. So activity duration estimation was dependent on the activity list and our resources. Once we have our activities defined and have an estimate for those activities, we can go about sequencing the activities. And this is where we got the idea of activity on the node or the project network diagram; it’s the visual roadmap of how you will get from the beginning of the project all the way to the end of the project. So the project network diagram visualises the flow of the work. And that’s where we had our predecessors and successors, and the relationship between the two.
Then we talked about finding a float. Recall that “float” is the amount of time that an activity can be delayed without affecting its successor activity or the project end date. Now, project float isn’t going to be a topic on which you’ll get a lot of questions for your project plus exam. You might have a few questions, so plan accordingly. Now, once we have our project schedule created, we may have to do some schedule compression. Remember, we have fast tracking. We allow activities to overlap. And then we also had crashing, where those activities that are effort-driven require more resources to get done faster. Finally, we have scheduled the work that we want to do, controlled our schedule, and ensured that we are adhering to our schedule baseline. All right, great job. Keep going. I know you can do this.
