SPI fields

The SPI (schedule performance index) field shows the ratio of the budgeted cost of work performed to the budgeted cost of work scheduled (BCWP/BCWS). SPI is often used to estimate the project completion date. The timephased version of this field shows values distributed over time.

There are several categories of SPI fields.

Data Type    Percentage/Number

SPI (task field)

Entry Type    Calculated

How Calculated    Project calculates SPI as:

SPI = BCWP / BCWS

Best Uses    Add the SPI field to a task view to display or filter for the ratio of work performed to work scheduled. This information can help you see how far ahead or behind schedule tasks are.

Example    You have a four-day task, and its total planned budget is $100. After two days, the budgeted cost of work scheduled (BCWS) is $50. However, after two days of actual work, 60 percent of the work has been completed, for a cost of $60. The SPI is 1.2, indicating that you're ahead of schedule.

Remarks    An SPI ratio greater than 1 indicates that you're ahead of schedule. Likewise, an SPI ratio less than 1 indicates that you're behind schedule. For example, an SPI of 1.5 means that you've taken only 67 percent of the planned time to complete a portion of a task in a given time period. An SPI of 0.8 means that you've spent 25 percent more time on a task than was planned.

The SPI field is available by default on the Earned Value Schedule Indicators table. With a task sheet view displayed, open the More Tables dialog box and apply the Earned Value Schedule Indicators table.

SPI (task-timephased field)

Entry Type    Calculated

How Calculated    Project calculates SPI as:

SPI = BCWP / BCWS

The timephased values for BCWP and BCWS make timephased values for SPI available.

Best Uses    Add the SPI field to the timephased portion of the Task Usage view to display or filter for the ratio of work performed to work scheduled. This can help you see how far ahead or behind schedule your tasks are on a timephased basis.

Example    You have a four-day task scheduled for Monday through Thursday, and its total planned budget is $100. After Monday, the budgeted cost of work scheduled (BCWS) is $25. Actual work for the task is reported on that day as 20%, for a cost of $20. Reviewing the field in the Task Usage view with the timescale set to days, you see that the SPI for Monday is 0.8 or 80 percent, indicating that the task is behind schedule. However, after Wednesday, 90 percent of the work has been completed, for a cost of $90. The SPI is now 1.2, which is displayed for both Tuesday and Wednesday in the Task Usage view, indicating that you're now ahead of schedule.

Remarks    An SPI ratio greater than 1 indicates that you're ahead of schedule. Likewise, an SPI ratio less than 1 indicates that you're behind schedule. For example, an SPI of 1.5 means that you've taken only 67 percent of the planned time to complete a portion of a task in a given time period. An SPI of 0.8 means that you've spent 25 percent more time on a task than was planned.

In addition to the timephased SPI, you can show total SPI for tasks in the sheet portion of the Task Usage view. Either add the SPI field to the current table or apply the Earned Value Schedule Indicators table, in which the SPI field is included by default. With a task sheet view displayed, open the More Tables dialog box and apply the Earned Value Schedule Indicators table.