In project management terms, a variance is the difference between the anticipated state of the project and the actual state at a particular point in time. At the beginning of the project, when the planned schedule, budget, scope, etc. have just been calculated, the actual state and the predicted state are exactly the same. There are no variances. This is the point at which the project should be baselined.
As time progresses, the execution of the project may not follow the plan exactly. For example, if a task starts later than it was scheduled to start, there is a difference between the baseline Start date and the actual Start date for the task. The actual Start date is later (greater) than the baseline Start and the difference between these two dates is a positive number – there is a positive variance. As you can imagine given this example, a positive variance is unfavorable. In this case, where a task is late to start, subsequent tasks may also be delayed, and the recalculated schedule may show a Finish delay. (more…)
In our last post, we introduced the basics of variances and demonstrated how to isolate for unfavorable Work Variances. It is equally important, however, to analyze how your dates are progressing. If Baseline Work is 1,000 hours, Actual Work is 500 hours, and Remaining Work is 500 hours, then Work is equal to 1,000 hours and Work Variance is zero. Sounds pretty good, right? But what if you are 8 months into a 10-month project? Assuming an even resource load, you should have consumed 800 hours by now, but your actual work is only 500 hours.
This example highlights the importance of analyzing Start and Finish Variances in addition to Work Variances. If we were to look at the Start and Finish Variances in this 1,000-hour project, we would most likely find that tasks are not starting or completing on time. (more…)