Thursday, April 16, 2009

What is Effort Variance?

Effort Variance

Effort Variance = [(Actual Effort - Planned Effort) / Planned Effort] * 100

It provides variance of Actual Effort vs. Planned Effort.

As an example suppose the Quality Objective is that the Effort Variance should not exceed 5%.

Project X

Planned Effort = 80
Actual Effort = 95

Effort Variance = (95-80)/80 x 100 = 18.75

Project Y

Planned Effort = 110
Actual Effort = 115

Effort Variance = (115-110)/110 x 100 = 4.55

The effort variance may come out to be more than expected (e.g. we estimated that it will take 100 hours but in actual it took 110 hours, +10% effort variance)

Some of the causes why this variance might have occurred are:

Effort Variance Estimation parameters were wrong.
Effort Variance Scope was not understood in totality.
Effort Variance Inefficient process.
Effort Variance Someone changed the estimate without changing scope just to make the number match the preferred schedule
Effort Variance Added capability the customer did not request.

The effort variance may come out to be less than expected (e.g. we estimated that it will take 100 hours but in actual it took 90 hours, -10% effort variance)

Some of the causes why this variance might have occurred are:

Effort Variance Estimation parameters were wrong.
Effort Variance There was an improvement in the process and brilliant work was done.
Effort Variance We did not complete the task and probably missed on one or more requirements.
Effort Variance Missed out on some steps.

Also See:
Schedule Variance & Cost Variance with Example
Defect Density
Defect Removal Efficiency
Test Coverage
Test Effectiveness