Schedule Performance And Variance Indicator
Earned Value Analysis is a method of tracking the status of a project. It is based on numeric parameters and provides a transparent and un-biased snapshot of the project situation. The Schedule is tracked by means of Earned Value (EV) and Planned Value (PV) parameters.
EV is calculated as the total amount of required planned staff-hours for those requirements that you already accepted.
PV is calculated as a piece of the project Budget. The amount is shown in staff-hours that were planned to be spent by today (staff-hours are divided evenly across the completed requirements.)
Consider the following example, we have 5 requirements, today is the 25th day of the project. The total Budget is 615 staff-hours, and total project duration is 40 days (this is a snapshot of requirements attributes table):
| # | Requirement | Size | Status |
|---|---|---|---|
| R1 | User can manage account | 145 | accepted |
| R2 | User can upload video | 80 | accepted |
| R3 | Admin can manage users | 120 | accepted |
| R4 | Admin can view reports | 180 | implemented |
| R5 | Admin can filter users | 90 | specified |
EV is the sum of 145, 80 and 120 staff-hours (all of the requirements that are accepted so far). EV is equal to 345 staff-hours.
PV is the result of 25/40 days that have been put into the project (0.625), and then multiplied by 615 staff-hours. PV equals to approximately 384 staff-hours. According to the plan, we have to deliver 384 accepted staff-hours to the customer on the 25th day of the project.
SPI is calculated as EV/PV and equals to 345/384 = 0.898. That means that the project is behind schedule now and corrective actions are required.
This example shows how the project can be tracked without excess technical details. This information (EV, PV and SPI) is presented to you at each Iteration Acceptance Meeting (by the end of each Iteration) and is available instantly online in our management software.
The SPI should always be equal to or greater than 1.0. This is a key aspect for the project manager. If an SPI is less than 1.0, the project manager immediately impelements corrective action, which could be one of the following (depending on other project characteristics):
- Add more resources
- Change the scope by moving requirements to the next release
- Re-estimate the project and approve a new Schedule and Budget (worst variant)
The numbers presented by an Earned Value analysis help you, the project team, and project manager to stay on the same page during the course of the whole project.
Earned Value data is not meaningful during the Inception Phase, when Specification is not yet approved. Following the LCO Milestone is consensus, the project manager will start to calculate the SPI.
