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The 4 Types of Activity Relationships in Project Management

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Published on December 27, 2021

Business operations for enterprises everywhere are inextricably driven by networked technology. And as new systems are being designed, they are increasingly complicated to develop, deploy and hand-off to operations. As all that technology is brought on-line, it's sort of counter-intuitive to say that a human skill set is key to success. Of course, we are talking about project management.

Without proficient project managers, it's unlikely that many of our sophisticated systems would see the light of day, let alone be deployed and used effectively by the intended users. And it's not just in IT that project management is essential.  New product launches, introduction of new employee benefits plans, and new marketing campaigns are all examples of complex initiatives that must be managed.

Qualified project and program managers are in-demand and certifications such as the Project Management Institute's Certified Associate in Project Management (CAPM) and Project Management Professional (PMP) are highly valued by hiring managers.

We thought that it would be useful to delve into some key aspects of the project management role. In this article we will discuss logical activity relationships. In future articles, we'll look at the main functions for which a project manager is responsible, how management and leadership skills apply, and the stand-out actions that can make or break a project manager.

Introducing Activity Relationships

At the simplest level, projects are about a set of activities or tasks that must be completed in some defined sequence by individuals or groups of individuals, within certain timeframes, and using a specific set of resources. There are a defined set of relationships that can exist between the start and end points of these activities.

For example, you would be wise not to begin the activities to build a house until you have completed buying the land on which it is going to sit. In another example, you cannot begin to pour the concrete for the foundation until you begin to mix the concrete, but you don't have to mix it all — that is finish the mixing — before you start the foundation slab. In project manager lingo, "Mixing the Concrete" is known as a predecessor activity to "Pouring the Slab". In the same way, "Pouring the Slab" will be a predecessor activity to "Erecting the Walls". So, each activity can be a successor and a predecessor activity to one or more other activities.

Project managers need to define the relationships or dependencies between all project activities before they can chart out their project schedule. That includes determining the predecessor and successor relationships between all the project activities.

There are four possible activity relationships, which are defined in the Project Management Institute's "bible of project management" — The Project Management Body of Knowledge (PMBOK®). The relationships are Finish-to-Start, Start-to-Start, Finish-to-Finish and Start-to-Finish.

We searched around for a good techie example that would demonstrate as many of these relationships as possible. We found one in Cisco's Small Business Resource Center, where they outline the steps to set up a router. Some of the relationships are rarely seen, so we'll have to be creative.

1. Finish-to-Start

The Finish-to-Start relationship means that one activity — the predecessor — must be fully complete before any following — successor — activities may begin. In our Cisco example, you must "Finish" deciding where to install the router, before you can 'Start' the next (successor) step of plugging it in!

Finish-to-Start is the most common activity relationship in project management. Our example has several of them. For example, a certified network admin would finish configuring a wireless router gateway, before starting to connect it to the router.

2. Start-to-Start

The next relationship we will look at is Start-to-Start. In this case, an activity cannot start until and unless another activity also starts. What would one of these relationships look like? Let's go to our Cisco router example and tweak it a little. Let's imagine that we have multiple, rack-mounted routers and we need to slot them in and then connect them to the internet. Slotting in the routers is the predecessor activity and connecting them to the internet is the successor.

Now as soon as one admin starts to slot the routers into the rack, another could start to make the internet connections. The activities don't have to finish at the same time and in fact they don't have to start at the same time. The second admin does not need to start to make the internet connections immediately, but the first one MUST have begun to plug the routers into their rack slot.

3. Finish-to-Finish

This relationship exists where two or more activities can only be considered completed when both are completed. Say in our Cisco example, you were also bringing a new server online. You would need to load and configure the server operating system and you also must connect the server to the router. These are examples of finish-to-finish activities. Configuration of the server OS cannot be considered complete until the server is connected through the router to the network.

Now, the task of loading and configuring the OS can begin independently of the task of connecting to the router. However, to ensure a fully functioning server on the network, both activities would need to be completed.

4. Start-to-Finish

And finally, we come to the Start-to-Finish relationship! This relationship is rarely found in real-life projects. In start-to-finish relationships, as soon as the predecessor activity starts, the successor activity will finish. Think of it as one switch goes on and another goes off, like in a cut-over to a new system.

Probably the best example for us would be if you are migrating to a new system. Let's say in our Cisco example, that we're installing a next-generation router to replace a tired old one. You can't finish disconnecting the old router until the new one is up and running! Starting the "Go Live" activity for the new router is the trigger to finish the 'Disconnect' activity for the old one!

Wrapping Up

Activity relationships are the raw material on which project schedules are built. They are just one of many technical aspects that project managers must master. Let's face it, becoming a competent project manager requires a mastery of a wide range of techniques, combined with some important business and management skills. If you are thinking of project management as a career option, then the certifications that we mentioned from the Project Management Institute (PMI) are well-worth your consideration.

If you do not have a track-record in project leadership, and/or you don't have a four-year degree, then the PMI's CAPM is your best bet.  If that's your path, then check out CBTNuggets' Certified Associate in Project Management (CAPM)® online training. Business productivity trainer Simona Millham will take you through the project lifecycle from start-to-finish and help prepare you for the CAPM certification exam.

Once you clear that hurdle, you'll be able to set your career sights on the Project Management Professional (PMP), which is acclaimed by CIO magazine as the'gold standard' in project management certifications.


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