Observed Requirement

16 September 2008

Here's one of my favorite software development quotes:

Requirements are the things that you should discover before starting to build your product. Discovering the requirements during construction, or worse, when you client starts using your product, is so expensive and so inefficient, that we will assume that no right-thinking person would do it, and will not mention it again.

-- Suzanne and James Robertson

It's the opening paragraph of the first edition of their book "Mastering the Requirements Process". As regular readers might guess, my liking isn't connected to agreement. I like this quote because it sums up the waterfall value system to requirements (indeed the word 'requirement' is inherently waterfallish).

Agile methods violate this underlying assumption by intending to discover the 'requirements' during construction and after delivery. But even this cavalier disregard of the above sage advice is nothing compared to what many leading web sites do these days. These sites explore requirements by observing what the users do on their sites and using that information to generate ideas for new features along the following lines:

  • Look at what people are trying to do with the site and provide easier ways for them to do it.
  • Look at where people are abandoning doing something, and look for ways to fix whatever was frustrating them.
  • Build a new feature and see if people use it.
  • Build an experimental feature and make it available to a subset of the user base. Not just can you see if they like it, you can also assess how much load it puts on your servers.

To support this kind of analysis, you need to add user logging behavior into the application and build some tools to analyze these logs. Much logging appears for free in web applications, which I suspect was major impetus for people starting to do this. But the logging, and analysis, can go further as it's added to the application.

I haven't found much advice out there on the web on how to do this, and I don't hear much discussion about doing this in practice. Like many things it requires a concentrated effort to spend the time to build monitoring capability and then to use it to probe how to improve the software. Furthermore it's a mighty step away from how the traditional software process, even for agile projects.

But there is a huge potential here. Everyone knows how big the difference is between what people say they want and what people actually need and use. By watching what people actually do with your application, you can find out what actually happens with the software - which can give you much more direct information than other sources. As a result I think more teams should consider adding this approach to their toolkit.