Writing stories is not the JOB of a Business Analyst in agile development. Writing stories is a collaborative effort in which Customer, BA, Dev, QA should all take part. This is the N in the INVEST principle.
As everything in life should start, we start by defining the problem. Waterfall is an approach that borrows heavily from Einstein’s idea of a deterministic universe. The idea is that
If you know the position and velocity of each atom in the universe, you can accurately determine the state of the universe at a given point in future or the past.
The point is that this is just a theory. I am not contradicting the theory but I am just pointing to the simple fact that gathering knowledge about the position and velocity of each atom takes too much time to be of any use.
Waterfall tries to do the same thing at a very small scale; at a project level. And the argument remains the same. It’ll take you too much time to understand every aspect of a problem for you to be able to successfully solve it while it’s worth solving.
Agile is about improvisation. You accept the inherent randomness of the universe. This might be genuine randomness OR it might just feel random because we are not able to understand it, but at any rate the universe is random to Human Beings.
So we say, given that things are going to change in ways that cannot be determined, let’s do our best to adapt to those changes as quickly as possible. To adapt is to understand what has changed, how it affects us and what can we do to “maximize our happiness” in the given situation.
This is where you require the key component of anything worth calling a success. Collaboration.
In the deterministic world of waterfall, the Business Analyst is supposed to be this wizard, who understands the whole problem, whose affected and how and formulates a solution to it all by herself. Few have succeeded at meeting this unrealistic expectation.
Agile says let us all work together towards solving this problem and I think that’s a more realistic way of getting an optimum solution. Now what this means is that nobody’s word is final on any solution unless everyone is happy. Neither the client, nor the Business Analyst and nor the Developers. That is what it means when we say that a user story is Negotiable (i-N-v-e-s-t).
* Increasing happiness as in the sole purpose of life.