PMI CAPM – Plan and Control Project Time Management Part 5

9. Activity: Finding Float

All right, welcome back. Here’s an activity for you to practise finding a float on the critical path. This is what the float exercise looks like. It’s a resource for you in this lecture here. So you can download this as a PDF. However, if you really want to emulate your exam experience, draw this out by hand. So they’re going to show you a graphic like this. And they might say, “How much floats on activity F?” Or if I delay activity C by one day, how long can I delay activity H? So you’re going to have to draw this whole thing out and calculate float in the exam. So take your pick. You can print it out; that’s fine; or, if you want to, you can draw it out. So we’ll give you a moment to do this.

Or you can pause the course here, and then we’ll take a look at some questions for you. Now that you have calculated float, you’ve done the exercise. Some questions. If activity E is delayed by two days, how much can activity G be delayed? If the duration of activity D takes three additional days, how long will the project take to finish? And then, if activity F takes eleven days to complete, what’s the earliest day that activity G will be able to finish? All right, on the next slide, I’m going to show the answers. So if you’re still working, you may want to pause this, finish the exercise, and then we can walk through it together. So maybe I’ll see you in just a moment. But here’s a warning. I’m moving forward in three, two, and one. Right now, here’s what the activity answer looks like. I know it looks really messy, doesn’t it? So I’m going to walk through this. So, for our paths, the first thing I like to do is write down all of the possible completion paths.

So we can go to Abegi, and that will take 20 days. I just added up the duration. I can also go to Abdgi, and that takes 16 days. I can leave now. That’s 22 days. And I can go AFGI, and that would take 21 days. So our critical path, and you can see I have it there in purple, will be acFh and I. So now we can begin our forward path. We’ll start with activity A. A has an early start. Day one. One plus three is four, minus one is three. The earliest I can start activity is b.

Day four will be activity C. On activity B, four plus four is eight; minus one is seven. On activity C, four plus two is six, minus one is five. Now pause for a moment. not the video. Pause our conversation. Notice I didn’t just continue on from B to E to G to I. You follow the flow of the work. So you do this as if these were in columns. So in other words, I always find the early start and early finish for each activity based on its predecessor; I don’t hop all the way over to E and G; I’m going to do E next and then D and then F. So I follow the flow of our project network diagram. So let’s go to E. The earliest day that E can start is one day after B is done. So its early start is eight. Eight plus five is 13, minus one is twelve.

Activity D can start one day after B is done. Eight plus one is eight minus one, or eight plus one is nine, minus one is eight. The earliest activity F can begin is one day after C, so that’s days six and eight, which is 14 minus one, equals 13. So look at activity G. And this is why we do this in this order. The earliest that activity G can begin is dependent on the earliest that Ed and F can finish. So I’m taking the largest early finish of the predecessors. So activity G cannot begin until day 14 because E finishes on day twelve, D on day eight, and F on day thirteen. So I have to take the largest number here on the forward pass, so G can’t start until J 14. Let’s go ahead and do activity G here; 14 and six are 20, minus one is 19. Activity H can start on day 1441, and seven is 21, minus one is 20. Activity I performs the same function. I take the larger of the two predecessors, earlyfinish, so I can’t start till day 21, because G and H have to be done. So day 22 is activity I, 21 and two, minus one. So that’s the early finish for Activity I. Now for the backward paths.

So the latest I can finish I is also the earliest I can finish I. So I just dropped that number down to 22 and then took the backward path: 21 minus two is 20, plus one is 21. Those numbers are going to match, remember, because it’s on the critical path for activities G and H, and the latest I can finish without affecting I is one day prior. So activity G’s late finish will be 2020; minus six is 14, plus one is 15. Activity H: Actually, we’re going to do the shortcut here. So for HFC at A, we can just drop those values down.The values of early start and early finish for anything on the critical path will be the same as late start and late finish. So, if you notice that the numbers, the values for the finish and the starts on acFh and I, those in purple, are the same, you’re on the critical path because the difference is float. There is no float on the critical path. Let’s go back to activity G. So we do our formula: 20 minus six is 14, plus one is 15. This is important. So the earliest I can start G is day 14, and the latest I can start G is day 15. So, Ed and F, the latest they can finish is one day before 15 o’clock. So 15 to E will be 1415, and to D will be 14. But look at activity F.

Activity F, the latest we can finish it, is day 13 because it has two successors. G and H are dependent. If I take activity F to day 14, that means instead of eight days of duration, it will take nine days of duration.And now my project will go out to day 23. So on the backward pass, I have to consider, just like we did in the forward pass, the predecessors to the node that I’m calculating. Okay, activity E: 14 minus five equals nine; plus one equals ten. Activity D: 14 minus one is 13, plus one is 14. Activity B has to be done by day nine in order for E to start no later than day ten. So that’s why it’s nine, not 13. Activity B: Nine minus four is five, plus one is six.

And then, of course, we do the difference of the two on Beg and D, and that will show our float. So how much float do you have on activity B? Two days. How much float do you have on activity D? Six days. Right. The difference between 14 and eight is two days, which is how much time you have for activity E. And what about activity G? You have one day. So you need to remember that our example we did earlier was just really simple, but as your project gets more complex, you can’t just find the difference between the two paths, because there may not always be just two paths. You’re going to have to really do this and expose the float. Let’s look at these float questions here.

So, some speculative questions. If activity E is delayed by two days, how much can activity G be delayed? So activity G, if we look at activity G here, if we had two days for that path of activity G, it’s going to take us out to 22 days of duration. Now, what I’m doing here—remember, we wrote down all the paths in the corner. So rather than do all the math up here in that path, I’ll just say if you increase it by two days, that path, well, I’ll go to every path where G exists and just add two to that activity. So, if I had two days, AC, F, G, and I would get me to day 23. So I’m going to be late.

So our answer here is that if activity is delayed by two days, one path will be 22 days in duration. See, I caught myself. It should be 23 days in duration. Let’s look at that. The path that G is on, ACF G and I, takes 21 days. So if G takes two days of float, which he doesn’t have, and only has one day of float, its duration will be 23 days. So that’s a good catch. It’s a good lesson. It’s almost like I planned it that way. All right, if the duration of ActivityD takes three additional days, how long will the project take to finish? So again, I’m going to hop back.

Let’s look at Activity D. How much float do I have on Activity D? Well, I have six days afloat, which doesn’t really affect the project. I’ll still be done by day 22 because I was allowed to delay it up to six days. If Activity F takes eleven days to complete, what’s the earliest day that Activity G will be able to finish? So if we go look at Activity F, if it were to take eleven days instead of eight, that would be an eleven. So six and eleven would be 17, minus one would be 16, which would then tell us activity G could not start till day 17. And then it would also change our critical path, right? because we would have more days of duration there.

The critical path would increase because right now there’s no float available for Activity F. Those are the types of questions you can expect on your exam. So you want to spend some time going through this lecture, going through these exercises, making up some more on your own, but really understanding float. Now, again, you’re not going to have a tonne of questions on the exam. You’ll most likely have two or three. So just be aware of that as you prepare and really understand how to do the forward pass and backward pass and find flow. All right, good job. I’ll see you at the next lecture.

10. Consider Resource Availability for Scheduling

When we manage our time or the schedule for a project, we always have to consider resource availability for scheduling because resource availability really affects the activities of the project, the duration of those activities, and when the project can get done. So in this lecture, we’re going to talk about some attributes of resources and how they affect scheduling. The first stop here is resource levelling heuristics. Remember, heuristics are just a guideline. Resource levelling means that you equalise the total amount of labour that can be used in a time period. So, for example, in this little histogram at the bottom of this bar chart, each one of those bars, those different colour bars, represents a resource on our project.

We have a heuristic that says you can only work 40 hours per week. So, if you’ve scheduled people to work more than 40 hours, as in this case, we’ll have to level the playing field. So we have to lop off that time and move it to next week. So when we do resource leveling, we’re at 40 hours a week. So it’s going to cause our project duration to increase. So resource level and heuristics typically extend the project schedule. Another term here, or a couple of terms,  is “schedule compression,” which means we’re trying to compress the overall duration of our project.

The two terms you need to know are “crashing” and “fast tracking.” Crashing implies adding more people and labour to your project. Well, crashing adds people, but it also drives up costs because you also have to pay for that labor. Fast tracking allows for activities, but most phases overlap. And sometimes you’ll see this in a really big construction project where the foundations are being built over here, but over here on this side, they’ve already started the framing, and they kind of chase each other around that construction project.

And those phases overlap just based on the size of the project. As a result, time can be saved. Rather than saying the entire foundation has to be built, the entire skeleton of the building, and so on, those phases can overlap. However, fast tracking introduces risk because if you’ve already begun work based on a problem in an earlier phase deliverable, you’ve already begun work based on that risk. Rather, you’re going to have a big problem undoing work to fix what may have happened in an earlier phase.

So fast tracking adds risk, but it also allows phases to overlap. Monte Carlo simulation is a piece of software where you can play what-if scenarios. So a good example of Monte Carlo simulation is that we could say if these activities come in at the early optimistic time and this set of activities come in at the most likely time, but these over here come in at the pessimistic time, what will that do to our project?

So I can do multiple combinations and play what-if scenarios to predict a likely outcome for the project. The simulation is called Monte Carlo because that is where all of the gambling takes place. not all of it, but it’s famous for gambling. So you think about a roulette table where the ball goes around and can land on any one of those numbers. Then, depending on where you place your chips on the roulette table, there are various combinations of possible outcomes based on where you place a chip and where the ball lands. But that is a Monte Carlo simulation that represents the possible combinations of events. Then we have our next activity here. Our next thing to talk about is the schedule development process.

The next process for us is creating milestone charts. Milestone charts show when milestones are likely to happen in the project and then show when they actually did happen. So, just as we saw with the histogram, we can see that there is variation in the bar charts. We have project schedule network diagrams, which we’ve already looked at, and we are visualising the project work. So let’s hop in here and really talk about controlling the schedule. So to control the schedule, we have a schedule change control system. We measure project performance, we examine schedule variants, and we update the project schedule based on changes, defects, rework, or whatever the conditions may be that are affecting our project. You may have taken corrective action, and you are going to have lessons learned that are applied throughout the project, not just at the end of the project. So we’re done here for control scheduling.

The project management plan, the actual project schedule, work performance data, project calendars, schedule data, and OPA’s tools and techniques to control schedule performance reviews, project management software, resource optimization techniques, modelling techniques, leads and lags in schedule compression are all available.

And you could use a scheduling tool like Project or Primavera. Our outputs include work performance information, schedule forecasts, change requests, project management plan updates, project document updates, and OPA updates. All right, measuring project performance So when measuring project performance, the value is tied to the percentage of the work that you’ve completed. Setting us up a little bit here for earned-value management that we’ll talk about in module seven of the Pinbox cost management system, planned value is where we say this is what the project should be worth at this point in time.

Then we have a couple of formulas to estimate and complete. How much more will you need to reach the end of the project? We have an estimate for completion. Where is your project likely to end up based on where you are now as far as its final cost? We have milestones. So how are we hitting our milestone dates? Are we lagging?

Are we ahead of schedule? Are we right on? And what about key deliverables? So our requirements, traceability matrix, and what deliverables were actually created as opposed to when they were planned to be created? Do we have any variances throughout your project? You’re likely going to have to do some performance reviews. So you’re looking for trends? Are you consistently late or consistently early? So are your estimates poor or overestimated? You’re too aggressive? You’re going to do some critical path analysis? Those what-ifs are like our exercise we did earlier, the critical chain method. We want to take a look. How much of our feeding buffers are you using if you take that approach? Are they effective, and are our resources being utilized? properly earned value management, which we’ll look at in the next section on cost and schedule forecasting. So are we ending our plan? All right. Good job finishing this section. I know we talk an awful lot about an awful lot of things, but a really important module and section for your exam So good job. Keep moving on.