Does your software Testing Pay – Part 2

“Does your Software Testing Pay” is the question we posted two weeks ago.
There are obviously two parts to this question, one is how much it costs and the other is how much it saves.

The cost portion is reasonably easy:

1. Chargeback rate on resources (means hours per release must be recorded).
2. Equipment and space usage (if not included in the above).
3. Test Tool cost (amortized over all the projects)
4. Opportunity cost if the resources should be engaged in something else.

The savings portion is somewhat harder:

What would each found defect have cost to fix in production? This is obviously an estimate.  One calculation is supplied below.

1. Look at each defect found by testing.
2. Estimate the probability of it occuring after release of the code to the users. You might want to take estimates from several people and average them. Either the probabilities must be between 0 and 1 or else you need to convert to a figure between 0 and 1 before using it.
3. Estimate the cost to the organisation under the assumption that the defect does occur in production. This cost includes the direct costs to the company (fixing, testing and deploying); the indirect costs (administration etc) that are often hidden (Iceberg – 9/10 of the costs are hidden)
4. The cost of the customers in rework, lost data, inability to respond proerly.
5. Add up the costs per defect and multiply by the percentage.
6. Add up the resulting figure for all defects found by testing for a release.

If Savings > Costs your software testing is paying for itself.