Estimate Activity Durations

00:01 Hello and welcome.

00:03 This is an overview of the estimate activity durations process from the PMBOK guide.

00:10 It's very important that you pay particular attention to this module and the other time management planning modules as well, because they all culminate in the development of the project schedule and in the exam, there's always quite a few questions about the development of and the representation of the project schedule. And you will probably have to complete a network diagram as well. The difficulty level is rated as high.

00:39 Because most of these concepts you may not have come across before nor used in your day to day job.

00:46 And as such, with the new concepts that we're introducing to you, there's a moderate or medium level of memorization required for this particular module.

00:57 The estimate activity durations process itself is part of the project time management knowledge area.

01:04 In fact, it's one of six planning processes in this area, and those six also have a seventh process are monitoring and controlling a process called control schedule.

01:20 The estimate activities, duration process comes after the defined activities process, the sequence activities process the estimate activity resources process because each of those previous processes provides necessary information to enable us to put together individual estimates of activity durations.

01:42 And once we've done that with all of that information combined, we can then go on to develop our project schedule.

01:49 So do pay particular attention to this module, particularly the estimating techniques that we're going to introduce to you.

01:58 The good news about those estimating techniques is they're also used in cost estimation as well.

02:04 So you'll see them again in that module.

02:09 The estimate activity durations process helps us understand.

02:14 The following domain task.

02:16 And remember, the exam is based on the domain tasks.

02:21 In this instance, it's planning task for develop the project schedule based on the approved project deliverables and milestones, scope and resource management plans in order to manage timely completion of the project.

02:36 And in fact, that single domain task task for covers all six of the time management planning processes.

02:46 So it's all about planning, what you're going to do with your project schedule, then doing it to create a project schedule.

02:56 The key themes of this estimate activity durations process.

03:00 Well, it's to use all of the previous information from each of the other time management planning processes.

03:09 Taking that information and estimating a duration for each activity, once we've got individual activity durations, we can add all of those up to give us a total project duration.

03:25 Let's start with the inputs.

03:28 And there's quite a lot of inputs here when you think about all the information that you could use to estimate duration, there are quite a few.

03:36 So let's start with the schedule management plan.

03:39 Of course, as the planning document that guides our time management activities, it will provide guidance on the methods, the tools and techniques we're going to use to estimate activity durations.

03:53 It will also provide guidance on the expected accuracy of our estimates.

03:59 And how we do rolling wave planning and successive iterations and get better at our estimates as well, so ensure that you have your scheduled management plan and of course, that's an output from the plan schedule management process.

04:14 Well, you may also want our activity list and activity attributes.

04:18 These are both outputs of the defined activities process one of the earlier time management planning processes.

04:26 Because of course, this these things, the activity list and activity attributes give us all the information about the activities that we're going to do on the project.

04:35 And of course, what we're seeking to do here is to estimate a duration for each of those activities.

04:43 We may also want our individual activity resource requirements.

04:47 Now these are an output from estimate activity resources.

04:51 The immediate prior planning process.

04:55 This gives us the resources that we have available to complete the activity work.

04:59 And of course, if we've got senior more experienced staff to do the work, they may do it faster but cost more.

05:07 If we've got junior staff, they may do it slower.

05:11 That cost less, and therefore our duration estimate will be more.

05:15 We may also want the resource calendars, which are an output from some of the human resource management processes.

05:22 These tell us when resources are available, what sort of work week do they have? When as vacation time? When are they not available? Because they're part timers.

05:32 So we need the resource calendars because this will affect the durations.

05:36 And remember, that activity duration can mean two things the duration of the activity can refer to the amount of work taken to do the activity.

05:45 For example, an activity could take two days.

05:49 But the duration could also refer to the amount of time it takes to do that two day's work. You may not be able to do it in two days because of resource constraints.

06:00 Maybe they're not available two days a week and therefore that two days work could actually take a week to complete because the resources have other commitments.

06:10 This is particularly the case in week matrix or functional forms of organization, where the resources may not be allocated full time to your project. So take care when estimating activity durations that you're clear about the actual duration of the work to be done.

06:29 That's important for cost purposes, but in the actual time taken to do that work, that's important for the project schedule.

06:38 We may also wish to go get our project scope statement.

06:41 This is to double check that we've captured all of the project's scope, but also to see which parts of our project scope have been well defined and which ones are subject to rolling wave planning and still yet to be defined because we can't do activity duration estimates very accurately for those parts of the project scope, which are yet to be defined.

07:03 We may also wish to have our risk register, and that's, of course, as an output from some of the risk management planning processes because the risk register will identify key areas of our project that are subject to duration, estimating risk and we need to know those now so we can take that into account and perhaps add contingency reserves for time at this point in the project.

07:30 We may also want our resource breakdown structure, which is an output from the estimate activity resources process.

07:38 It'll tell us all the resources that we have available to us because at this point, with estimating durations, we may want to provide feedback to that particular process and do another iteration of that.

07:50 We may want to change the resources that we have available to us if the durations don't stack up, if they're taking too long.

07:57 We may go looking for more senior staff rather than junior staff or bigger machinery rather than smaller machinery.

08:04 And of course, like many other processes, we may wish to use enterprise environmental factors, government regulations, industry standards which affect how long tasks take, and also organizational process assets such as our project management methodology or any blank templates we've got for estimating activity duration.

08:30 So we take those particular inputs that are useful to us, and we can apply any of the following tools and techniques that we find useful in order to develop our individual duration estimates for each of our activities.

08:43 The first being exPERT judgment and as we know, exPERT judgment is the most popular tool within the Bot guide and you are an exPERT. Your project team members who are actually going to do the work are very valuable exPERTs as well, and you should always ask the people who are going to do the work for their duration estimate of the work. Don't be the sort of project manager who tells people how long the work will take.

09:14 You won't get an accurate estimate, but X, but more importantly, you won't get buy in from your team.

09:21 So always take the time to ask the team members who are going to be doing the work for their duration estimate of the work.

09:29 It's generally more accurate.

09:31 And you'll also get buy in from them.

09:34 But just a word of warning people tend to give estimates that they think you want to hear.

09:42 Usually, this is overly optimistic estimates, so just be aware of that when asking people for their estimate of the activity durations.

09:53 The next estimating technique that we may want to use is analysis, estimating now analysis estimating simply means taking an analogy, something similar we've done before and using that to forecast the duration of an activity we're doing now, and we'll have a closer look at that in a moment. Another tool in technique that we may wish to use is parametric estimating.

10:20 Now, in this instance, the word metric is simply Latin for number . So parametric estimating takes two numbers and multiplies them together to get a duration estimate for activities.

10:35 And we'll have a closer look at that one in a moment too.

10:39 One of the formula that you're going to need to take into the exam is the three point estimating formula.

10:47 So in those first few moments in the exam when you're writing down your brain dump include the three point estimating formula as part of that brain dump.

10:57 It's useful when we have a scenario of an optimistic estimate, a most likely estimate and a pessimistic estimate.

11:07 It's a little bit of a formula we can use to help put in an actual number based on those three figures.

11:14 We'll have a look at that in a moment.

11:17 Another total technique, we may find useful group decision making techniques. Things like brainstorming the nominal group technique where you get the group to figure out which ideas should go forward or perhaps the Delphi technique.

11:33 The Delphi technique is a great way to solicit information from exPERTs anonymously and avoid peer pressure, bullying or groupthink.

11:43 We'll have a look at that again in a moment to reserves analysis with any duration estimate, you should be prepared to put in a contingency reserve now.

11:54 A contingency reserve is for known unknowns.

11:58 It's for known uncertainty or identified uncertainty in your project.

12:02 And there's many methods to do it using historical information, such as we know that we routinely underestimate our activity durations by 10 per cent perfectly valid way of adding 10 per cent onto your duration estimates.

12:17 There are also more sophisticated methods of developing reserves as well, and we'll look at those more closely when we come to do quantitative risk analysis.

12:28 Analysis estimating is simply taking a similar activity from a previous project to estimate the duration of an activity we're about to complete.

12:38 So for example, we may have completed a project recently say in the last year where a particular activity took two days to complete.

12:47 And we know that this time around, the activity is twice as big.

12:51 So our analysis is to make would be four days.

12:56 Obviously, the great thing about analogous is debating as it can be done very quickly.

13:01 But the accuracy may not be what we need at this point, depending on how relevant the information about the previously completed activity is and how good our estimate of the magnitude of this activity is compared to that one.

13:16 We're also seeing analogous estimating used later on in our cost estimating module.

13:22 So look out for that.

13:25 Parametric estimates take one number and multiply it by another number to give us our duration estimate.

13:33 So for example, if we know that we can excavate 10 meters of trench a day and we have 30 meters to do so, our time estimate, well, that's three days for that particular activity.

13:46 We're taking two numbers and multiplying them together, and we will also see parametric estimating as a valuable tool and technique for the cost estimating processes as well.

13:58 Now, pay particular attention to 3-point or PERT estimates. There will always be questions in the exam which require you to calculate three point estimates.

14:11 They're often called PERT estimates because they are part of the program evaluation and review technique, which also gave us things like activity on know diagrams and the critical path method.

14:22 So you may sometimes see it referred to as the PERT formula.

14:26 The more proper name for it, though, is the three point estimating technique because we have three points.

14:32 We have an optimistic estimate, a most likely estimate and a pessimistic estimate.

14:38 Now there are two forms of this formula.

14:41 The more uncommon form of the formula is to simply add up those three estimates the optimistic the most likely in the pessimistic and get a simple average from them, in which case we would divide by three.

14:55 And that would give us a simple average of those three numbers, and that would be the number that we would put into our activity duration estimate.

15:04 A more complex form of the equation, though.

15:08 Takes those three numbers.

15:10 And here you'll see the formula is T for time, we'll see this exact formula appear and cost estimating with that T replaced by a C for cost.

15:22 So I choose to remember it without the T and without the sea and simply as our optimistic plus four times our most likely plus our pessimistic estimate divided by six.

15:36 And this time what we're getting is a weighted average, not as simple average.

15:41 Remember, for the simple average, we simply divided by three because there were three numbers with the weighted average.

15:48 There are now six numbers.

15:50 There's a single optimistic number, a single pessimistic number, but there is for most likely numbers.

15:58 Obviously, we are giving greater weighting to the most likely estimate now, as an aside, you can get quite complex with this and change all of those weightings. As long as it adds up to six, there's plenty bits of software that will help you do that.

16:14 However, for the exam, it's one optimistic, one pessimistic and for most likely, and we take those and divide by six. Once we have that, we can also calculate a standard deviation.

16:30 Now, the standard deviation we can use to give a range of certainty of delivery of a particular duration estimate, and we'll have a look at an example in a moment. Now, the actual formula for standard deviation is very complicated and something that statisticians would love to look at.

16:48 Our formula that you need to remember for the exam is what we call a heuristic or rule of thumb. It's a very simplified version of the big standard deviation formula.

16:58 And in this instance, we're simply going to take our pessimistic from it, subtract our optimistic and divide by six.

17:08 P minus o divide by six gives us our standard deviation, and I'll show you an example of that in just a moment.

17:18 There is another variable we can get, and it's called the variance.

17:22 And it's simply the standard deviation squared.

17:26 Now for the purposes of the exam.

17:30 You need to know if you're presented with the variance and asked to calculate a range of uncertainty.

17:37 One standard deviation two standard deviations.

17:40 Three standard deviations.

17:41 Either side of a mean the first thing you must do to that variance is to calculate the square root of it to get the standard deviation.

17:49 Watch out for that in the exam.

17:52 So let's take a look at some examples.

17:55 Here we have the three point estimate.

17:58 Let's say we have a pessimistic estimate of 15 days for a particular activity, an optimistic estimate of five days for a particular activity and a most likely estimate of eight days.

18:12 This is how we would calculate our three point estimate.

18:16 We would take five plus eight times for plus 15 and divide that by six.

18:23 So we get five plus 32 plus 15 divide by six, which gives us 50 to divide by six, which gives us a three point estimate of eight point sixty six days.

18:37 And that's the estimate that we would put into our activity duration estimate if we were using that technique.

18:46 For your exam study, make sure you put extra emphasis on understanding this formula and doing some calculations to make sure you get the right number.

18:59 Let's take a look at standard deviations now, standard deviations are useful to determining the total amount of a population within a normal distribution.

19:10 And we know that one standard deviation either side of the mean contains 68 per cent of the total population and that two standard deviations either side of a mean, contains 95 per cent of the total population and three standard deviations either side.

19:28 The mean contains ninety nine per cent of the population.

19:33 As an aside, and as we'll see when we come to quality management, six standard deviations, or Six Sigma contains ninety nine point nine ninety nine per cent of the population.

19:45 But for now, we just need to know one standard deviation, two standard deviations and three standard deviations either side of the mean.

19:52 And you will need to know those figures for the exam.

19:56 So let's take a look at our previous example, where we had a mean of eight point sixty six days.

20:04 You'll recall we had a pessimistic estimate of 15 days and an optimistic estimate of five days.

20:11 So let's calculate our standard deviation.

20:14 It's our pessimistic minus our optimistic divide by six.

20:19 So in this case, it's 15 minus five divide by six, which gives us 10 divide by six, which is one point sixty six days. Therefore, we could say if we wanted to express a 68 per cent certainty that our range was, we are 68 per cent certain we could deliver this activity in eight point sixty six days plus or minus one point six six days.

20:49 Or if we wanted to say with ninety five per cent certainty the range at which we could deliver this activity, we would say it's eight point sixty six days plus two standard deviations, which is three point thirty two days.

21:05 And that's the value in determining a standard deviation to be able to communicate a range of certainty and uncertainty for a duration estimate. So make sure you take into the exam those figures for standard deviations. Sixty eight per cent for one standard deviation.

21:22 Ninety five per cent for two standard deviations, ninety nine per cent for three standard deviations and no, the formula.

21:30 And once again, even though t for time as present in this formula, I prefer to remember it simply as p minus.

21:37 So over six, because it's exactly the same formula when we come to cost, except the T is replaced by a C.

21:46 Group decision making techniques, I've mentioned them already, but let's take a closer look at some of them.

21:52 What we're trying to do here is to get a group of people to come up with some ideas, using group creativity techniques and in terms of tools and techniques, and then PMBOK guide. There is a big overlap between group creativity techniques and group decision making techniques.

22:08 There is a big overlap here.

22:10 I've combined the two, so we may get a group of experts together and we want a particular decision made.

22:17 So first up, we start with brainstorming about all the particular decisions that we could make. We could use the nominal group technique, which is then taking all of the ideas and decisions that we could make.

22:29 Remember in this instance about individual activity duration estimates.

22:34 And we asked the group to vote on which ones are further worthy of further exploration. That's the nominal group technique.

22:42 One of my personal favorites, though, is the Delphi technique.

22:46 Think about this if you have a group of exPERTs together in the room and you ask for their opinion.

22:53 What normally happens is the loudest person wins.

22:57 Introverts, junior staff tend not to speak up so much, the Delphi technique helps us get around that instead of bringing people together in a room.

23:06 What we do is invite them to participate in our survey or information gathering. We don't tell them who else is involved in the survey.

23:16 We give them questions and we ask them to provide their considered responses to those questions. We then take all of those responses and send them out to all the participants in the Delphi technique.

23:28 And without identifying any of the other authors, we ask them to read the feedback received and if they wish to, they can then change their answer based on their. It's a great way not only to get creative creative techniques, but to also get decisions made.

23:44 So once we have those.

23:47 Another thing to think about is when you're trying to make decisions, particularly about duration estimates is the actual way that final decisions will be made.

23:56 Here are some useful techniques to consider before making the decision about how the decision will be made.

24:03 Will you have a consensus, as in the decision will not be made until everybody agrees on the particular duration estimate? Will you require a simple majority? Or will you require a firm majority before you agree to that decision, or will you appoint a single decision maker whose job it is to take everybody's opinions on board and then make the decision? It's worthwhile giving all of these things sorted out beforehand, and they could all be captured in your schedule management plan.

24:39 The outputs that we may produce from estimate activity durations are our individual activity duration estimates.

24:48 And once again, the information about each of the activities in our activity list is now growing.

24:54 We have the resources allocated to them by the previous process is to make activity resources. And now we have individual duration estimates, estimates allocated to them as a result of this process.

25:07 But remember, we still don't have a project schedule that comes next. We may also choose to update significant and relevant project documents like our Schedule Management Plan or parts of our project management methodology as part of our continued commitment to continuous improvement. So in summary, the estimate activity durations process takes information from the previous time management planning processes.

25:38 And applies that to give us individual time estimates for each activity. Thank you.

25:46 This has been an introduction to the estimate activity durations process in the PMBOK guide.