Assume that as of the date of our status report, we have the following status on the indicated tasks in a construction project.
WBS element Planned Value Earned Value Actual Cost Cost Variance Schedule Variance CPI SPI

Interior
Roofing $18,000 $17,500 $17,000
Interior finish $0 $0 $0
Marketing and Sales $1,600 $1,800 $1,900

The Planned Value for each of these was computed by multiplying the planned number of hours of work to the status date (e.g., 18 days - 144 hours for the Roofing task) by the standard rate for the assigned workers (e.g., $125/hour for the Roofing crew). Thus the planned value for the Roofing task as of the status date is $18,000. The EV and AC numbers for the Roofing task mean that we've done less than we planned on the task, and also spent less than we planned.

a. find out the Cost Variance, Schedule Variance, Cost Performance Index (CPI), and Schedule Performance Index (SPI) for the three low-level WBS elements ("Roofing", "Interior finish", and "Marketing and Sales").

b. How does CPI compare to 1.0 for each WBS element, and what does that tell us?

c. How does SPI compare to 1.0 for each WBS element, and what does that tell us?