Join Chris Croft for an in-depth discussion in this video Using network diagrams, part of Project Management Simplified.
- Now we come to stage four of the planning process, which is to think about the running order of the tasks. At this stage, people quite often jump straight to a Gantt chart, but you mustn't. You must do what I call a Post-It Note diagram first. The posh name for these things is a Network diagram or sometimes a PERT chart, but basically, it's fine to call them a Post-It Note diagram, because that's what they are, really. What I've done is I'm imagining here that I've got a little project, I'm going to open up a distribution center in a foreign country.
I've brainstormed my tasks. I've got to decide which country, I've got to get a manager and some staff, I've got to buy a site. These are just in a random order, the order that I've brainstormed them in. What I'm going to do is have a little think about how I'm going to do this project. This really is the heart of my planning process. If you find yourself thinking, "Ugh, I don't know how to even begin to plan that project. "I don't know where to start." That's a sure sign that you need to do this process. What I would probably do is I'd think, "Well, I'm going to choose the country first, "get the manager quite early on.
"The manager can choose the staff. "I need to decide on the site, "I'd probably find the site and then I would buy it. "I'm probably going to have to modify "the buildings after I've bought it." Of course, you could always write extra Post-It Notes if you realize there's a task you've forgotten at this point. Buying the furniture, I think I'm going to get the manager to choose the furniture. Then, once we've modified the building and bought the furniture, we can install it.
Opening is going to be the finish, so that's going to be there. Now, the permit, when should I do that? By the way, when you do this, I would recommend involving your team as well, rather than just doing this on your own, which you can. Why not involve your team? They'll enjoy being involved, and they'll all have a say, and even if they've had no planning, they'll understand, they'll get this, and they'll be able to help. The permit, I think I'm going to get the permit while I'm finding the site. I'm probably not going to buy the site till I've found it and got the permit. I don't think the manager is connected to the permit.
So that looks like roughly the right order. The next thing I can then do is draw my arrows in to be sure. Once I've chosen my country, I'm going to get the manager, the permit, start looking for the site. I can't buy the site till I've got the permit. Then once I've bought the site, I can modify the building. The manager is going to get the furniture and the staff. Once I've bought the furniture, I can install it, but I also need to have modified the building before I install the furniture.
Then I can open once I've got the furniture in and the staff. At this point, I might remember that I've forgotten staff training, let's say. I could write one more Post-It and stick it there, but for sake of illustration, that's my plan. You can see that that's not going to take long. In real life, it might take you 20 minutes. Involve your team; it's verging on fun, it's a great part of the project process, and it'd be a real shame to miss this out. There are two reasons why we want to do this. One is to get the running order worked out, but the other reason is to find the longest path through, because that's going to tell us how long the project's going to take to do.
From my previous estimating, I'll know how many weeks each of these are taking. Let's suppose that choosing a country's going to take me four weeks. Recruiting a manager's going to take me six. The permit might take maybe 10 weeks. Quite a lot of bureaucracy there. I could probably find the site in five. Buying it, maybe that's another 10, and modifying it, let's say is eight. It doesn't matter whether these are accurate. It's just an illustration. Recruiting the staff might take me eight weeks.
Buying the furniture may be only a couple of weeks. Installing the furniture, a couple of weeks. Opening takes me no time at all, because opening is an event. I've put it on because it's good to have a finish event. Sometimes you have events half-way through as well, and that's fine. An event is just something that has zero duration. So you can still put it on as a Post-It Note and just have a zero there. The main thing is we're putting the times on the boxes of all of these, not on the arrows. So we can now look for our longest path, and there are complicated mathematical ways of finding longest paths.
I can't be bothered with any of those. It seems to me that it's obvious where the longest path is. You can look at this, you can immediately see the longest path goes through here. That's my longest path, isn't it, because I can see that the six and the two are shorter, the six and the eight is shorter than all of this. My longest path, if I add this up, I can see that's 10, 20, 30, so 34 weeks is how long this is going to take me. I now know that that's the length of my project, and I can now ask myself, "Am I happy with the 34 weeks?" If I'm not, then I need to speed it up, and we'll come to that in a minute, because that's going to be step five.
I've got a project plan, I know it's 34 weeks, my team have been involved in drawing it up, which is great. I know these are the critical tasks, and these other tasks are non-critical or floating tasks. This one, for example here, it's a five-week task, and it's got to be done after this and before this, and you can see that there are 10 weeks happening while we get the permit in between. This has basically got five weeks of float. This one here would be a bit more difficult to work out the float, but you can see there's eight weeks to do those two, that's an eight there, so we've basically got 20 weeks of float, 20 weeks of choice about when we do those two.
Float will be much clearer when we make this into a Gantt chart, which we're going to do later. I've got the critical tasks and the floating tasks, and I suppose the main thing is to make sure that the critical ones are accurately estimated, because if finding the site actually takes six or seven, it doesn't really matter. Similarly, these, they can be wrong by a fair amount. It's not going to affect the overall time for my project, but these ones, which are forming the time that I'm going to promise my customer, they have to be correct. It's sometimes worth going over a second time and really making sure that you've got these estimated.
That's the Post-It Note method for getting a critical path diagram drawn, or sometimes known as a PERT chart. If you're starting a project, I really would urge you to do this before you start trying to create a Gantt chart. If you jump straight to the Gantt chart, it'll be much more difficult to draw it, and it will be wrong. Just spend 10 or 20 minutes with your team creating one of these first, and then later, make it into a Gantt chart.
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- Defining project scope
- Deciding how to list tasks
- Estimating costs and time
- Planning for risk
- Staying on budget