The premise of all the "DD" acronyms is to minimise technical debt in one way or another and otherwise drive us to being lean.

The motivation for this article is "writing the minimum amount of code" in the spirit of Agile in general and TDD/BDD specifically. As someone who has developed code for more than a quarter of a century, I have learned that anything I write as code will be used against me as long as the software is in use. I don't want to write more code than I need to in order to justify my reward. In this case, my reward is to have the RDD monitor set off an alert that serves as feedback to knowledgable people to make decisions about the product such that I will continue to be rewarded.
So, what is RDD?

TDD instructs us to write as little code as we can to assure a passing set of tests.
BDD instructs us to write as little code as we can to assure a valuable set of features.
I'd like to extend these guides to a methodology that instructs us to write as little code as we can to assure a specific level of business returns (i.e. ROI). I'll call it RDD for fun. Returns Driven Development (thanks to my fellow ThoughtWorker Kyle for coming up with the name!).

In most cases, there is an underlying business case for creating or modifying software. Of those, some are justified by a business plan that shows how much more money the business would make if only the requested features were implemented. Of those, only a few are borne of a real market analysis. In the rest of the cases, the primary motivation is the product manager's intuition that it would be nice to have these new features.

I wanted a way for the product owner to convey her ideas about the modifications, without regard to her motivation. RDD is a way to describe software feature requests without having to make up financial data to justify the requests. It's also a way to validate the intuition of the product team.

Some examples:

Our customer acquisition rate will increase if we made signup easier.

Our salespeople will sell more licenses if they could demonstrate the software at trade shows with preloaded customer accounts.

Our sales will increase if we exposed our B2B services to the public Internet.

All these sound valid points for a product manager to present as justification in embarking on a technical investment in creating or modifying existing software.

The only change I would make to the above examples is to add a quantity. Acquisition rate will increase by 30%; we'd have 25% more sales etc.

This is the starting point of RDD: in order to assure the growth of this business, we need to increase sales by X%.

Now that we have that statement, it will be scrutinised by the company's board and a decision will be made regarding its implementation. If action were to be taken, RDD is now charged by proving those statements.

RDD assures statement validation by providing business feedback to the product owner that the course charted is indeed driving towards that stated goal. The sooner and more precise the feedback, better decisions will be made to adjust the statement or the course of action.

RDD proposes to set up the monitors first and develop minimal software to satisfy them. The monitors will provide a baseline of the current situation and, prior to development, will indicate whether the premise was indeed factual and worthwhile.

As an example, an RDD monitor will state:

Generate an alert if the number of the daily sales of licenses is below 30 or is in decline more than 5% week over week.

Generate an alert if the number of B2B API calls originates from more than 10% of our customers.

Primarily, the alerts will indicate movement in their business domains and will set a baseline of alert frequency. They can also serve as indicators that something is not functioning on a technical level, but that's secondary as other IT alerts exist for that purpose.

Now comes the fun, DD, part:

The monitor's premise is dependent on much more than meets the eye at first reading.
The data for the alarm may not exist. The transaction table may or many not exist, depending on the state of the product that the alarm is set to monitor. If this is a new product, a transaction data source may actually have to be created just for the monitor. That alone is an excellent improvement to the organisation.
Following that scenario, a data table without data is not much use; enter BDD. Enter TDD. Soon, you may have developed the app from scratch. A whole system may have been created as the result of a Returns statement made by the product manager, yet we invested the minimal amount of development needed to satisfy the monitor. Feedback is guaranteed as the monitor was implemented up front even before the software was.
RDD is also effective when extending existing software as well, while assuring that the minimum code was written to satisfy the monitor's goal.
The claim that a simple sign up form will boost customer acquisitions will soon be proven right or wrong. The monitor will raise an alert if signups have increased week-over-week. If it does not, we may need another monitor that observes another aspect of the product that questions its value to the users.

So, the next time you are involved in a product's inception or new feature, start with business monitors!

Try asking for a business returns monitor from the operations group. At first, their mouths will open and close but without words coming out. Soon after, they will realise that it is nothing but another monitor. You then employ DDD/BDD/TDD To develop it and the system that feeds it information. You then sit back and wait for the product owners to request new monitors or features as they attempt to regulate the reported data to prove their original claims either right or wrong, or a little of both.