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Technical Debt and Business perspective

By Jean-Louis Letouzey on jan 27th, 2012, no comment

A new concept: Non-Remediation Cost

The current version of the SQALE Method Definition Document supports and helps to manage the Technical Debt of an application/project. The new version of the method (which will be publicly released soon) will continue to use the debt metaphor and help you to manage two concepts:
•    The Technical Debt, which is now well understood. (If needed, you will find more detail here. If you want to know everything, there is the complete reference book from Chris Sterling here). I remind you that the SQALE Quality Index is an objective and precise estimation of the Technical Debt accumulated within a piece of source code.
•    The Non-Remediation Cost, a new concept, which I want to introduce here.

I will introduce the Non-Remediation Cost concept with a simple analogy.
Let’s imagine that you need a new office building. So, you write a specifications document, which contains your functional requirements and also your quality requirements. Here are two examples of such quality related requirements:
•    For security reasons, you require video cameras at strategic locations of each floor
•    For thermal insulation reasons (or whatever reason), you require that all windows have double glazing.

If during the building phase, you or the building team discovers some non-conformity regarding these requirements, the building company will evaluate the remediation cost of the issues in order to understand their relative importance and their impact on the project’s planning and budget. The useful information during all the building phase and the concept which will be used by the development team is the “Technical Debt”. The Technical Debt is a relevant measure to manage non-conformities during the building phase.

Let’s suppose that very close to the delivery date, you visit the building for control and you discover 5 single glazing windows and 2 missing video cameras. As there is not enough time to fix the 7 issues, you will be obliged to find a compromise. Which information will help you to make the smartest decision, the best compromise?
In fact, you will look after the cost of leaving the non-conformities and you will try to answer the following question:
What will be the impact of leaving simple glass window against missing cameras in some places of the building?
At that moment, what counts is the business perspective. That means the real or potential damages resulting of the non-conformities. The monetization of the damages can be summarized as a cost which is transferred to the client and/or the owner, that’s what is called the “Non-remediation Cost” (you also may call it the “Business Debt”). The Non-Remediation Cost of each issue will be compared to its Technical Debt in order to set remediation priorities.

To summarize the metaphor:
The cost of fixing a non-conforming window is a Technical Debt, that’s the cost that the building team will have to pay to fulfill its commitment.
The extra heating cost (and the total monetization of all other damages) resulting of keeping a non-conforming window is a “Non-Remediation Cost” transferred to the owner – the business, and resulting of the delivery of a non-conformity.

Non-Remediation Cost applied to source code quality

Now, if we apply both concepts to source code:
First I remind you that within SQALE, source code quality is simply compliance to source code related requirements.
The Technical Debt represents the cumulated negative impact of the non-conformities on the real development cost of the project. The interest of that debt is a decrease of development productivity.
Technical Debt will impact the figures of the Development Plan.

The Non-Remediation Cost represents the cumulated negative impact of the same non-conformities on the real business value of the project. The interest of that debt is a decrease of the project’s ROI. Non-Remediation Cost will impact the figures of the Business Plan.

Both concepts and the metaphor apply to all types of development methods (agile or not). Both concepts are the monetization of stated non-conformities.
The Technical Debt represents the technical perspective of the findings; the Non-Remediation Cost (or Business Debt) represents the business perspective of the same findings.

How to use both perspectives

When you just want to monitor source code quality, you just want to monitor “how far” you are from your quality requirements. Then you will mainly monitor and analyze your Technical Debt.
If you want to optimize your quality versus your effort, then you will use both concepts, both information, the Remediation Cost and the Non-Remediation Cost. You will spend your limited remediation budget on remediations with the best ROI. That means, you will try to decrease your transferred costs (Non-Remediation Cost) while spending the less remediation effort.

The following graph illustrates the usage of both concepts.

I think the new concept just provides the means to manage the remediation’s priority as you manage the feature’s priority:
Priorities regarding the implementation of functionalities are established by taking into account associated development costs and business values.
In analogy, the remediation’s priority of non-conformities is established by taking into account associated Technical Debt and Non-Remediation Cost. The analogy is illustrated below:

In conclusion, the two concepts provide two different perspectives, two different pieces of information for analyzing and managing the non-conformities of your code. The Technical Debt is a first level indicator for day to day monitoring. The Non-Remediation Cost is a second level indicator for performing optimization, compromise and setting priorities.
The new version of the SQALE Method Definition Document (coming next month)  will support you with relevant indices and indicators.

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