PMI CAPM – Plan and Control Project Time Management Part 4

7. Develop the Project Schedule

We’re now going to talk about developing the project schedule. This is always one of the most popular topics when I teach this course because it includes the cumbersome activity of finding the critical path and letting it float. So let’s hop in and we’ll walk through this in a logical order, and then we’re going to talk all about flotation and how you find the critical path. Developing the schedule means defining the sequence of events and the duration of the activities, which tells us the duration of the project and determines when resources are needed. It establishes logical relationships between activities. So it begins to create the flow of the work.

So it’s the sequence of when things should happen, in what order, with what resources, and then for how long. There are a lot of things to talk about in this section with Edo. So input the schedule management plan, the activity list, and the attributes, the project schedule network diagram, the activity, resource requirements, resource calendars, activity duration estimates, the project scope statement, the risk register, project staff assignments, resource breakdown structure, enterprise, environmental factors, and OPA. Those are all inputs, tools, and techniques. We have the idea of scheduling network analysis. That’s what we’ll be doing coming up. The critical path method is opposed to the critical chain method. Resource optimization techniques So how can your resources work better? How can you get it done faster? modelling techniques, discussing how to play some simulations? And what if the work flow leads and lags?

We’ve talked about that already. Schedule Compression What can you do to compress your schedule to finish faster? Then there are scheduling tools, which are my outputs here. I have a schedule baseline, the project schedule, schedule data, project calendars, PM plan updates, and project document updates. Let’s look at some project constraints here that can affect when activities can start or finish. The most restrictive constraint is that it must begin or end on. So this activity must start on December 1. So that’s a deadline in some regards—that it has to start on this particular date. It’s a constraint because all of the predecessors have to get done in time for that activity to start on December 1. “Must finish by” is a deadline, but that doesn’t mean you can get it done before it has to finish on this exact date. So finishing on time is also a constraint.

The next two are a little bit more flexible, where the activity can start no earlier than October 15, so it can start any time after October 15, but no earlier than October 15. So an example may be that sometimes you’re driving and you see a sign that says this road will be closed on or after October 15. It cannot begin before October 15, and it cannot begin on October 15, but it must begin on or after October 15. The next one will start no later than October 15. So you can start any time before October 15, but you have to have it started by October 15. The next two are polar opposites, but very similar. They’re a little bit more flexible than our must start and must finish, and that’s finished no earlier than January 12. Why would you want an activity to run all the way up to January 12? You might be doing testing, for example. So you have to continue to test and finish no earlier than October 12. So you want to continue that for a particular period. Now you can finish on January 12 or at any time thereafter. Finish no earlier than, but you cannot finish before the next one.

That is just a deadline. Finish no later than February 1, so you can finish any time before. Get it done early, but the last date you can reasonably get it done without causing a problem is February 1. So finish no later than This is a list of constraints you should be aware of. I’d guess you’ll have one question on these for your exam. These are also things you can do in the real world. If you’re interested, these are built right into Microsoft Project. All right, let’s move forward and talk about some assumptions in scheduling. A lot of times, when we have new work because of a change request, there might be some assumptions about how long it will take, or we can easily just drop it into the schedule. But new work can really cause some problems with scheduling because you might have to shuffle around resources and existing activities. So it’s not always easy to drop new work because of a scope change risk.

We might have some assumptions about our schedule—that our estimates are frequently overly optimistic, which could introduce a risk. A risk is an uncertain event. If you’ve never done this type of work before, then you really don’t know how long it takes. So we have to consider risk as an assumption, or all of our assumptions can become risks. Force majeure is an act of God. So we have a hurricane or an atornado, both of which cause disruption. A tree falls on the power lines, and that causes our project to go down. So we have an assumption that that’s not going to happen, but it could happen in labor. We also have an assumption that our labour is going to be available for the duration of the project. People leave, come, and go. People are on other projects, and it ends up taking longer than you anticipated. So that affects your project and then the effort that we assume a person’s level of efficiency will maintain at a particular level. Well, if they have things happening in their lives or distractions, or if they’re tired, their effort and efficiency can be related. So we have to make some assumptions here.

A good example of an assumption when it comes to labour and effort is the idea that I’m going to schedule Bob to work 8 hours on this task and it’s going to be done on Monday. We’re assuming that Bob has eight productive hours that day, that he doesn’t take a coffee break, make some phone calls, or have people drop by his office, and that he doesn’t quite get 8 hours in on your project, that he only gets in about 6 hours. So, assumptions, when it comes to labor and effort, we have to be aware that 100% doesn’t always mean 100% of the time that they’re contributing to your project. So we might say, “Well, out of 8 hours, we expect 6 hours of efficiency.” So those are some things to think about. Risk, as I mentioned, is an uncertain event or condition that can have a positive or negative effect on your project. Risks are often communicated as knowns and unknowns.

Now that we know these risk events are going to happen, we can respond to them. But there are probably some unknowns—some things lurking out there that we don’t know about—that could likely have an impact on our project. So we have to respond to those quickly. when we see those risk events lurking or when they come to light in our project. Risk analysis can also have an impact on project completion because it takes time to identify risks, conduct qualitative and quantitative analysis. It takes time to do that analysis, and that can affect our project completion. And, of course, there is the risk that they will occur, and we frequently focus on the money, the financial impact of a risk event. But there can also be a time impact because of a risky event.

So risk can definitely affect our schedule. Determining the project timeline: This is a Gantt chart that we’re looking at here. A Gantt chart shows us the duration of activities across the calendar. You can also use things like a flow chart and a project calendar. You can use a whiteboard. I don’t recommend that. But determining the project timeline is a way to visualise when things take place in the project. And, of course, this is just a screenshot from Microsoft Project, an old, old project that, for some reason, remained in my screen capture from 1997, when I was twelve years old. As far as you know, I don’t think my beard tells you otherwise. Right. All right, moving on. Effort and efficiency Effort and efficiency are not necessarily related. As I become more efficient, I don’t have to apply the same amount of effort.

So, like, we talked about installing those light fixtures. If I have 1000 light fixtures to install, the first time I do it, it might take me an hour, but I become more efficient. I develop a system. Well, it doesn’t necessarily mean that I’m going to be more productive. I might be more efficient, but I may still only do eight or nine a day. versus the total amount that I could do because I’m more efficient. And then alternative identification is something that we may have to do if someone leaves our project or a piece of equipment breaks down. So if Jane, the senior engineer, leaves, I might say, “Okay, what other senior engineers do I have?” I don’t have any, so I have to go with Bob, the junior engineer. Well, Bob is probably going to take longer. He can get it done, but not as quickly or efficiently as Jane did. Here we go. We’re about ready to talk about our project’s network diagram. This is a very simple project network diagram. This is called activity on the node, AON. And yes, there’s another flavour called AOA activity on the arrow, where the arrows represent the labor. We’re not going to worry about that.

We’re talking about AO. in activity on the node. The flow of the work always goes from left to right. So we go from A to B. A can also allow C to begin, where B, A, and C are all activities. So we start the project with activities A, B, D, and G. That’s one path through our project’s network diagram. And then we have ACF, and G is another path. If we were to add these paths up, if we were to say A, B, deg, if we were to add that up, so three and two are five, plus D is five, that would be 1016, and G is two is 18. So we would say that’s how long that path would take: 18 days. If we look at ACF and add those up, three and four are seven, four are eleven, and two are 13. So we have 18 days and 13 days. The critical path is always the longest path to completion. And yes, there can be more than one critical path. You might see that in one of our exams coming up. So there’s a hint. As a result, scheduled network analysis Our goal is to find the earliest completion date. It also tells us our latest completion date.

Most people think the critical path is the earliest thing you can get done. Okay, that’s true, but it also defines the latest that you can get done. You also want to be able to find opportunities to shift resources. And that’s the idea behind Float. You’re looking for opportunities to delay activities if you need to without affecting the start of the next activity or the project completion date. This is all about SWAT’s strengths, weaknesses, opportunities, and threats. All right, good job finishing this conversation. Don’t worry. Float; I’m going to set it aside in its own lecture. And so if you want to come back and review it, you can very quickly find it in the next lecture. So I’m going to set it aside, and we’re only going to talk about float in the next lecture. So hang in there. I’ve fired it up right now, so let’s shop in and we’ll knock this out. Keep going. You’re doing great. Eight.

8. Find Float in a Project Network Diagram

All right, welcome back. Now we’re really going to drill down into this topic of float. So remember this project network diagram that we looked at in the last lecture where we said A-B-D-E-N-G would take 18 days and the path of AC and FNG would take 13 days. Well, I’ve highlighted our critical path there in pink. That it’s. 18 days is our critical path, and then acfng—that is, activities that only take 13 days in duration—comes next. Activities C and F are not on the critical path. So as we’ll discover, there’ll be an opportunity to delay those activities without affecting the project end date. You cannot postpone abde or G. If you do, your project is going to be late. That’s why it’s called the critical path. It doesn’t mean those activities are more important. It just means it’s critical to finish those on time so that the project can end by day 18. In this instance, activities C and F will have some float. Float means there’s an opportunity to delay. They can flounder in that window. And the window represents the distinction between paths ABDEG and acfg.

So there’s about a five-day difference in float where those activities can move between days 13 and 18. All right, so let’s look at float. There are actually three different flavours of float. And everyone thinks of root beer floats when they hear that. I know I do anyway. Okay, so we have free float, and that’s one activity that can be delayed without affecting the start date of any subsequent activities. Total float is an activity that can be delayed without affecting project completion. So that’s five days. We saw in the last slide that it’s a total float. The amount of time that one activity can be delayed on its own is known as free float. So we’ll compare and contrast those that come up. In free float, you think about one activity; in total float, you think about all the activities on the path. That float, the project float, they kind of share. This one’s kind of unusual in that the whole project can be delayed without affecting the deadline.

So you usually have this situation where you’ve got a smaller project. Let’s say if you were to just crush it with your team, you could get it done in about 45 days. The project itself, though, isn’t due until the end of the year. So you have twelve months to finish that project, but it will only take you 45 days. So you could just crush it and knock it out. But it’s a low-priority project in your company, so you have other things that you work on, and you and your team kind of pick it up and put it down. It’s not in a huge rush on it.You have to wait until the end of the year. So that’s Project Float. Before we get too far into this, let’s get started and talk about how we find float. I always get people who write me and say, “Oh, I hate the way you do this; you’re horrible.” And then I say, “Mom, now what I tell these people is that if you have a preferred way and you get the same result that you like better, you should use that method.” I have no problem with that. I don’t care what method you use, as long as you get the right answer on your exam. Are we really going to do this in the real world? Are we going to draw this out? Probably not.

We’re going to use Microsoft Project, Primavera, or even Base Camp, I suppose, to do this business for us. So you don’t like the way I do things, and you know a different way because there are a couple of different flavors. Go ahead. Most of the time, when we learn something, that’s the way that we like it. So this is how I learned it and how I prefer it, and I’m going to teach it to you this way. Now I think it’s the most logical. What we do first is called the forward pass. The forward pass is that we try to find an early start. That’s the e in our formula. you see at the top. The early finish is the most we could possibly finish in activity. So go to Activity A here. Look at Activity A. Its early start is one. That’s the earliest that we could begin that activity. because you start on the first day of the project. The earliest you could finish that activity is after three days because this activity lasts for three days.

So let’s just put this on a weekday. Let’s say you start on Monday with activity A, and you know it’s going to take three days to get done. What day of the week would you finish? Well, you work all day Monday, all day Tuesday, and all day Wednesday on day three. So the formula at the top, what it’s doing, says you don’t take one plus three as four because that would mean you end on Thursday. So you account for that first day that the activity is in motion. And that’s why there’s a minus one. So if you start on day one and work for three days, one plus three is four. However, you are also working on day one. So you work Monday, Tuesday, and Wednesday. Early start plus the duration, minus one, is your early finish. So one plus three is four, and one minus one is day three. Now we can go to activities B and C. Look at activities B and C here. They can both begin as soon as A is done. So they’re going to start on Thursday, or day four. And whoever is in charge of those activities, are they going to work the entire fourth day? So let’s try our formula here. We say start day four on activity B early. The early start of four plus the duration of two is six, minus one is five. All right, let’s put it into our real world. Activity A: I begin on Monday, work for three days on Tuesday and Wednesday, finish on Day 3, go home, go to bed, return on Thursday, and begin Activity B. So that’s day four, and I finish on Friday, day five, because it’s two days in duration. I did three days of work on A and two days of work on B. So let’s go to activity C.

Activity C, the earliest it can start, is on day four because I have to wait for Activity A to get done. It is predicated on its predecessor, A finishing. So four plus four is eight, minus one is seven. So the early finish for C is seven. Let’s go to activity D. The earliest activity D can start is the day after B is done. So B will finish on day five, which means the earliest it can start is day six. Six and it’s duration of five. Six plus five equals eleven; minus one equals ten. The earliest I can finish on activity D is day ten. Let’s come down to activity F. What’s the earliest activity? Can F start? And on day eight, Y cannot start until C is done. As soon as C is done, F gets to start the next day. So it begins on day eight; that’s its early start. Eight plus four is twelve, minus one is eleven. Let’s go up to activity E. What’s the earliest E can start? Day eleven, because E can’t start until D is done. Because it is dependent on D, day 1111 and six equal 17, minus one equals 16.

Now look at activity G. What is the earliest activity? could really start? Can it start on day 17? Or why couldn’t it start on day 12? Because as soon as F is done, can’t G begin? No, it can’t. Right, you’ll probably say no, Joe, quit talking to me; this is weird. All right, so G cannot start until both E and F are done. So E finishes on day 16, even though F is done on day 11. G has to have both E and F because they both feed into it. So the earliest I could start G is day 1717; plus two is 19, minus one is 18. Now, notice I have the circle around 18 there. And look at our path at the bottom that we did earlier; that is day 18. Those two numbers—the duration of your critical path—and when you do this forward pass, those two numbers need to match. If those two numbers don’t match, then you did something wrong and you’ve made a simple mistake somewhere. All right, if you need to watch that again, let’s go ahead though. We’re going to move forward, and now we’re going to talk about the backward pass. So here on the backward pass, I’ve helped us out a little bit. I’ve got a critical path there in pink, but we’re starting at activity G.

The backward path you take starts at the last activity in your project. So, for activity G, and really all of our activities, we want to know what the absolute latest we can finish that activity without causing a problem or delaying the next activity. So we start at the end, and we work our way all the way back to so-called activity G. This will always be the case. The last activity in your project, the latest it can finish, will be the same number as the earliest it could finish. And that’s how we know it’s day 18, because you just take that 18 and drop it down. Now we want to know when we can start and still finish by day 18. So we do this backward pass formula where we take that late finish of 18 and subtract the duration, but we add one this time. So it’s kind of like our formulas reversed from the forward pass. So 18 minus two is 16. But we’re working all day 18. So 18 minus two is 16, plus one is 17. So on the forward pass, we did that minus one because we worked all of Monday. Well, here we’re adding it because we’re saying we’re working on all of the last day of that activity. So 18 minus two is 16, plus one is 17, and that’s our late start. Now, look at activities E and F. We want to say, “What’s the latest?” These activities could finish without affecting the latest activity G could start. So it’s just one day prior. So the latest activity E could finish is one day before the late start of activity G. So on Day E, we could finish by Day 16, and we’re okay.

On Day F, we could finish by Day 16, and we’re okay. What I mean by “okay” is that G isn’t going to be late. Let’s go down to activity F, so we know that the latest it could finish is day 16. We’ll take 16 minus the duration of four, which is twelve, plus one, which is 13. The earliest we could begin F is day 13. Because, consider this: if we begin F on day 1313, the latest we could begin, plus four days of duration, we will be finished on day 16. I work all of day 13, all of day 14, all of day 15, all of day 16, and activity G can still start on time on day 17. Notice all of the pink ones up here, the late finishes in red, and the early finishes in green. Those numbers match, as do the late start and the early start. So all the activities on the critical path will always be the same. Whatever numbers you have on the critical path for your early finish and your early start, you can just drop them because it will equal your late finish. Late start. Well, we’re going to do the math anyway, but that’s a little secret, a little shortcut for you. All right, let’s go up to activity E. We said the latest it could finish is 16. We’re going to use the formula across the top.

16 minus six is ten, plus one is eleven. The latest activity D can finish is one day prior. That brings us to day ten, from 11 to 1010. Minus five is five; plus one is six. The latest activity B can finish is one day prior to D. So that’s day five. Five minus two is three, plus one is four. Let’s come down to activity C. We’ll just wrap that one up. The latest activity C could finish is 1212, minus four is eight, plus one is nine. So that’s our late start for activity C. Now, the latest activity A can complete is on day three, one day before day B. It’s not day eight because, as you may have noticed, B and C can start as soon as A is finished. However, the latest it can begin is day nine. B, the latest it can start is day four. So our late start and late finish have to equal day four for activity B. In other words, activity B can start no later than day four. Therefore, activity A may finish no later than day three. So we plug our formula in. Our late finish of three minutes and three seconds is zero. Ha. There’s no such thing as “day zero.” So that’s why it’s one. And that is the backward pass. Again, you can’t watch that again, but I encourage you to do so. Or you can watch this whole lecture as often as you want. Let’s take a look at how to find float for an activity. If we look at activity F here, it’s one of the two activities that are not on the critical path.

The difference between the late finish and the early finish will expose float. So 16 minus eleven equals five days of float for activities F and C; the difference is also five days. I want you to also see something here on activity C or activity F. If we subtract the difference between the late start and the early start, it will also be five. So if you want to check your math, you can do the same on both sides of the finish and start, and it will be the same number. If it’s not, you’ve got a problem. It’s a math mistake. So activity C, the latest I can delay it, is five days. I can only postpone Activity F for five days. We now had the idea of total float and free float. The free float period for activity C is five days. For activity F, it’s five days. The total float between C and F is five days. I don’t get ten days of float because the duration of ACF and G is 13 days. So it’s a total of five days of float. So if I use three days of float on activity C, how much float can I have on activity F? I can have two days of flotation because I can use no more than the difference in the path duration. I have to be done by day 18. All right, so that’s the backward path.

Finding float necessitates some effort. I know you’ll probably have one or two questions on your exam, but now that you know how to do it, that’s one or two questions in your favor. I now have an exercise for you here to practise flows, coming up in just a second. So if you’ve been practising float, you’re going to go through this in the next lecture on float exercise. I also encourage you to create your own samples, draw, or just make up some crazy network diagrams and try it out. But as I mentioned, you’re only going to have a few questions on flow. So I’ll see you in the next lecture, where we’re going to walk through an exercise where you can practise flow.