A baseline is a snapshot of several task fields in time. These snapshots can be used to compare the current state of the project and what the state was when the baseline was saved. Views can be created to draw different bars for the different baseline start and finish dates so you can visually compare how tasks finished in comparison to the baseline. Typically, a baseline is saved just prior to the project starting so that it represents the planned state as it was just as the project was getting underway. A baseline includes the state of the Cost, Start, Finish, Duration, and Work fields. These fields are saved at both the task level and at the assignment level. At the resource level, a baseline contains the Cost, Work, Start, and Finish fields. The image seen here shows the Tracking Gantt view after a baseline has been saved and after several tasks have slipped to start later than planned.
- The dark bars represent the baseline for each task.
- The blue and red bars show the current state of the task.
- Task 1 is the only task that did not slip. You can see this because it is the only task with the colored bar in the same position as its dark baseline bar.
- Task 4 slipped one day and in turn pushed its successor tasks out one day each as well.
- Task 9 slipped two days.
A project can contain up to eleven separate baselines. The first baseline is called Baseline, which is followed by ten others numbered 1 “10. Commonly, the baseline called Baseline is used as the only baseline for the project (the one saved just before the project starts), and the other 10 are used to capture the state of the project at different points in time. Some project managers like to save one of these other baselines at the end of a phase or at a significant milestone. This creates a sort of trend chart for how the project moved and changed over time. This practice is particularly useful for projects that are long enough that a single point of comparison does not provide enough information about how the project changed.
Baselines are an important tool for knowing how well your project is doing in comparison to your plan. It is a best practice to save a baseline for your projects.