What is Earned Value Analysis (EVA) in Project Scheduling?

Earned Value Analysis(EVA) provides a quantitative indication of progress. The project manager uses this method to track the project. Proponents of the earned value system claim that it works for every software project irrespective of the kind of work. As a part of this, there is an initial estimation of the total number of hours of doing this project, with every task being given an earned value which is based on its estimated percentage of the total effort. In simpler terms, a project manager will be able to determine, through a quantitative analysis, how much of the project is actually complete.

As a part of this process, the following steps are needed to be done:
- The BCWS (Budgeted Cost of Work Schedule) is evaluated for each task that is included in the project. This estimation is done in terms of person-hours or person-days(if the effort is much more than a few hours). So, for a given work task its BCWS is the effort.
- All the BCWS that are calculated for all the tasks are summed up to get a value called BAC(Budgeted Completion).
- The next variable BCWP(Budgeted Cost of Work Performed) is calculated. The method to calculate BCWP is by taking BCWS value for all the tasks that have been completed(at any point in the schedule).

In simple terms, the difference between BCWS and the BCWP is that BCWS is the estimate for all task that was supposed to be done, while BCWP is the summary of all the activities that were completed.

EVA compares the planned amount of work with what has actually been completed, to determine if cost, schedule, and work accomplished are progressing as planned. Work is earned or credited as it is completed.

Earned Value Analysis
- compares like terms and is quick to apply in practice.
- requires the ongoing measurement of the actual work done.
- tasks that have not been started or that have been completed are relatively easy to quantify in terms of earned value.

How are the metrics determined for your application?

Objectives of metrics are not only to measure but also understand the progress to the organizational goal. The parameters for determining the metrics for an application are:

- Duration.
- Complexity.
- Technology Constraints.
- Previous experience in same technology.
- Business domain.
- Clarity of the scope of the project.

One interesting and useful approach to arrive at the suitable metrics is using
the Goal-Question-Metric Technique.
The GQM model consists of three layers: a Goal, A set of Questions, and lastly a set of corresponding Metrics. It is thus a hierarchical structure starting with a goal(specifying purpose of measurement, object to be measured, issue to be measured, and viewpoint from which the measure is taken).
The goal is refined into several questions that usually break down the issue into its major components. Each question is then refined into metrics, some of them objective, some of them subjective. The same metric can be used in order to answer different questions under the same goal. Several GQM models can also have questions and metrics in common, making sure that when the measure is actually taken, the different viewpoints are taken into account correctly.

Metrics are determined when the requirements are understood in a high-level, at this stage, the team size, project size must be known to an extent, in which the project is at a "defined" stage.