Critical Path

Quick reference

• 00:04 Hi, I'm Rey Sheen.
• 00:06 I'd like to talk about a very important element on project schedule planning on
• 00:10 schedule constraint projects and
• 00:11 that's the critical path analysis. >> The project management
• 00:17 body of knowledge, the PMBOK guide >> To find the critical path as
• 00:21 the sequence of activities that represents the longest path through a project,
• 00:25 which determines the shortest possible duration.
• 00:29 That means a critical path is the longest, but
• 00:31 not necessarily the most difficult of the project paths.
• 00:35 What counts is duration time.
• 00:37 Let me show you an example. >> This is a simple project
• 00:40 network diagram.
• 00:40 There are a total of eight task of varied duration and
• 00:43 multiple paths through the network.
• 00:45 Let's look at each of the three paths.
• 00:48 If we go along the bottom path, there are three tasks of two days each for
• 00:51 a total of six days.
• 00:53 If we start in the middle and then go low, there's one task of one day and
• 00:57 then two task of two days for a total of five days.
• 01:00 And three tasks.
• 01:02 If we follow the middle path, there are three tasks, each of one day for
• 01:06 a total of three days.
• 01:08 Finally, if we follow the top path there are only two tasks, the one is for
• 01:12 four days and one is for three days for a total of seven days.
• 01:15 That path has a fewest number of tasks, but takes the longest number of days.
• 01:21 Therefore, it is the critical path.
• 01:23 Any delay in the critical path delays the project completion
• 01:27 since all the other paths will complete before the critical path is done.
• 01:31 The critical path determines the final end date for the project.
• 01:35 As you might imagined,
• 01:36 knowing your critical path is very important on schedule constraint projects.
• 01:41 Critical path is normally calculated using software.
• 01:45 However, if you intend to sit for
• 01:46 the PMP exam, you must be able to do these calculations manually, since
• 01:51 you cannot take any project management software into the test facility.
• 01:54 I'll show you how to do that in another lesson.
• 01:58 Let's take a look at how we'd go about determining your critical path.
• 02:02 In order to calculate the critical path, you must have completed enough of
• 02:05 your project planning to know the relationships between the tasks.
• 02:09 And you must have a duration estimate for each task.
• 02:12 That means you're able to create a network diagram that shows the task and
• 02:15 relationships like I had on the previous slide.
• 02:18 If the project is a simple waterfall, meaning you do just one task at the time.
• 02:23 The critical path analysis doesn't add much information
• 02:25 because there is really only one path to the project.
• 02:28 By definition that path is the critical path
• 02:31 since it's the longest path through the project.
• 02:33 However when there are many parallel paths
• 02:36 the critical path analysis will determine which path is the longest and
• 02:39 therefore which path is one constraining the completion of the project.
• 02:45 When a project schedule changes, the critical path might change.
• 02:49 I've burn by this on a project, we are focusing on a critical path and
• 02:52 trying to accelerate it if possible.
• 02:54 We were successful accelerating in the critical path but
• 02:58 another path have been delayed and I wasn't watching it closely.
• 03:01 So although the original critical path became shorter,
• 03:03 the actual project critical path had changed and I was managing the wrong one.
• 03:08 The lesson is that when changes occur, recalculate your critical path.
• 03:13 I've said that critical path information is very important
• 03:16 on a scheduled constraint project.
• 03:18 Let's look at how you can use that information.
• 03:21 A good project manager manages the highest risk aspects of a project.
• 03:25 When the primary project constrain is schedule,
• 03:27 the highest risk aspect of the project is the critical path.
• 03:30 That is the path that will determine when the project will finish.
• 03:34 There's no schedule flexibility on the critical path,
• 03:36 all the other paths have some flexibility to accommodate issues and problems.
• 03:41 Therefore if a problem occurs on the critical path
• 03:44 I'll burrow resources from tasks that are under way on non critical path.
• 03:48 If those tasks are delayed,
• 03:49 it doesn't automatically mean a delayed to the project.
• 03:53 But if the critical path is delayed the project is delayed.
• 03:57 Another use of critical path information is when a project approaches a major
• 04:00 milestone I calculated and track the critical path into that milestone
• 04:05 Often little hiccups will occur as we approach the milestone.
• 04:09 The critical path calculation helps me to understand the impact and
• 04:12 prioritize the resolution of those problems.
• 04:16 Finally, critical path information is used to prioritize
• 04:19 any schedule acceleration techniques.
• 04:21 I apply selected techniques on the critical path
• 04:24 to accelerate the ending of the project.
• 04:27 We'll talk about those more in another lesson.
• 04:29 Applying the techniques on non-critical path tasks,
• 04:32 does not help the project complete any faster.
• 04:35 To accelerate the end of the project,
• 04:37 you must speed up the critical path. >> Understanding
• 04:42 which tasks are on the critical path will allow the project leader and
• 04:45 the core team to make better day to day project management decisions.

Lesson notes are only available for subscribers.