PMI CAPM Exam - Topic 4 Question 112 Discussion

This question utilizes the Earned Schedule (ES) method, which is an extension of the traditional Earned Value Management (EVM) framework. While traditional EVM measures schedule variance in currency (dollars/units), Earned Schedule measures it in units of time.

According to the PMI Practice Standard for Earned Value Management and references in the PMBOK Guide:

Identify the Variables:

Earned Schedule (ES): 16 weeks. (Note: In this specific calculation context, 'ES' refers to Earned Schedule---the duration that should have been taken to achieve the current earned value---rather than 'Early Start').

Actual Time (AT): 12 weeks.

Schedule Performance Index (SPI): 1.3 (given).

Formula for Schedule Variance (Time):

The formula for Schedule Variance in terms of time ($SV_t$) is:

$$SV_t = ES - AT$$

Substituting the given values:

$$SV_t = 16 - 12 = 4$$

Validation with SPI:

The formula for the Schedule Performance Index in terms of time ($SPI_t$) is:

$$SPI_t = ES / AT$$

Substituting the values:

$$SPI_t = 16 / 12 = 1.33...$$

This matches the provided SPI of 1.3 (rounded to one decimal place), confirming that the interpretation of the variables is correct.

Conclusion:

A positive Schedule Variance of 4 indicates that the project is 4 weeks ahead of schedule. This is consistent with an SPI greater than 1.0 (1.3), which denotes efficient schedule performance.