Gantt, PERT, or Task Calendar: Which Scheduling Model is Best for Your Project?

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With a new year comes new projects, and with new projects comes plans to execute them. These plans may work — or not. The key is to find the right model, or combination of models, that can help you schedule your projects more effectively. Here are three of the more common models.

Gantt Charts

Since the Gantt chart is one of the more popular project schedule formats, most people are familiar with how it looks. A horizontal axis represents time, while a vertical axis lists tasks/activities. Bars are used to illustrate the duration of each activity. These bars can be color-coded according to your needs. For example, using the same color for different bars can show task dependencies, who is assigned to the task, or what resources are used. You can also add lines and markers to specify milestones, notes, and other information.

When they’re useful: Gantt charts are effective for showing the big picture. Because smaller tasks are shown adjacent to each other in relation to the project as a whole, everyone in the team can see how their work will affect everyone else’s. This is especially useful for teams with remote workers. Gantt charts can also provide a useful template for projects with scopes and schedules that rarely change.

When they’re not: Since you need detailed breakdowns of project activities in order to develop Gantt charts, they may be difficult to implement in projects requiring many changes, such as in agile software development. The slightest change in dependencies, milestones, or tasks may force you to start a new chart from scratch. There are still ways to use a Gantt chart in these cases, but it’s not always the best choice.

The graphical representation in Gantt charts may also be unnecessary for projects that look more like the linear process of an assembly line, or for projects with only one or two participants.

Tools: If you want to try out Gantt charts, here are some apps you can start with:

Program Evaluation and Review Technique (PERT) Charts

The PERT chart illustrates a project by focusing on the relationships between activities. The structure of a PERT chart is similar to a flowchart or mind map. An important characteristic of PERT charts is accurate time estimates. Examples and instructions can be found at NetMBA and Edraw Soft.

When they’re useful: The layout of a PERT chart makes the relationships between activities easier to see than with Gantt charts. Thus, PERT charts can be effective for projects that include many activities occurring sequentially and in parallel. PERT charts are also more flexible; you need to make three different time estimates per task, which allows for mid-process changes.

When they’re not: Some people don’t like the math involved in computing the “expected time”, which is the average time it may take to complete a task if it were repeated. Here is a concise explanation of the formula, which may make it seem less intimidating. Another disadvantage of PERT charts is that they can be difficult to understand and follow, if the project has many complex dependencies and simultaneous activities.

Tools: Since PERT charts resemble mind maps or flowcharts, most mind mapping tools can help you create a PERT chart quickly. You can start with:

Task Calendars

Task calendars show the activities you need to accomplish each day, week, or month. Task calendars can be as simple as paper desk calendars or planners that are date or time based and have room for a to-do list each day.

Some calendars have blank spaces for a to-do list for items that don’t have to be assigned to a specific day. Some of them have indicators for task priorities, work-life balance, and task progress. David Seah has a number of different varieties of task calendars available from his blog,

When they’re useful: Task calendars are time-based, making them useful for those who are working on multiple projects at the same time. You can see the tasks you need to accomplish each day, week, or month, even if they’re attached to different projects. Breaking down tasks this way also makes them seem more manageable. Task calendars are also ideal for projects with simple, straightforward processes, since you don’t have to think about simultaneous activities or thorough time estimates.

When they’re not: Unlike Gantt or PERT charts, it’s not easy to see the connections, dependencies, and costs of your projects on a task calendar. Some calendar apps do give you the option to view only the tasks associated with a specific project, allowing you to check your progress for each project. Also, as the number of project participants increases, the daily task lists will become bulkier. This makes task calendars difficult to use for large teams, unless individual calendars are created for each participant. Because of these limitations, task calendars may be more effective when used in tandem with PERT or Gantt charts.

Tools: Most calendar apps allow you to create task lists or an agenda for the day, including:

There are also a few to-do list apps that have a calendar view. Todoist is one of them, though you have to type in a search query to get custom calendar views. I also recommend Worktrek, especially since it tells you whether you’ve had an efficient day or not.

While these three models aren’t the only ways to schedule your projects, they can provide a good starting point when figuring out your approach. Will you benefit from the big-picture thinking inherent in creating a Gantt chart? Or will a PERT model serve you better, since you’ll make several changes along the way? Is having a daily to-do list of deliverables enough? You can even use these different models together, if necessary. After all, no matter how you dress them up these models all aim to do one thing: help you get that project finished.

Have you tried any of these project scheduling formats? What are the benefits and limitations you’ve encountered?

Photo by stock.xchng user jnatiuk

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