"So when will you be done with this development project?"
I don't know about you, but I hate this question. There simply is no good answer for it. It seems like such a simple question with a simple DateTime valued answer. One of these days I swear I'll answer with, "Oh, I'll be done next Tuesday at 2:34pm." just to see what happens.
And seriously, businesses hate that we have such difficulty answering the question. It seems perfectly reasonable for them to want to know when they can plan to have the new processes that they know they desperately need. Developers demand high salaries and are ostensibly professionals, they should be able to give a professional answer, right?
The Road is Well Paved
The thing is, software development is a lot harder than people expect it to be--and this includes software professionals. Even simple software projects can run afoul of hidden complexities that can destroy well meaning estimates and make everyone unhappy. And no matter how you hedge your answers, people simply don't remember all your caveats, maybes, and what ifs that you use to indicate uncertainty.
The end result is that developers seldom make their ship-by dates and companies become disillusioned and impatient with all software development. That's not helpful for anybody, but it's pretty much the rule anymore.
And the fact of the matter is that the vast majority of developers (and development managers) never learn how to answer the estimate question. They'll move from company to company, repeating the cycle of hope, suspicion, and disappointment over and over again. Which works well enough for the developers in the boom times when the demand for development is so high that mildly talented house plants can get hired as developers.
So a lot of people are making the same mistakes over and over. Businesses can be excused for assuming that this is simply the way things are and feel confident in their distrust of software professionals. They've been there, done that, bought the t-shirt.
Paying the Toll
This environment causes developers who care about these kinds of things a lot of heartburn. Everyone pays for the ongoing cycle of disillusionment. I believe that this is what really prompts posts like the recent ones from Ted Neward talking about professional ethics. And I've been known to throw my own hat into the ring as well.
We get tired of paying for the sins of those who have gone before. And I'm not referring to the messed up legacy code we stumble into, either. Frankly, messed up code is the least of your problems coming into a situation with a client who has been burned by previous developer promises. Companies that have had deadline after deadline missed have a degree of mistrust that is very hard to overcome.
We pay for this distrust in a hundred different ways. The thing is, trust is a paying commodity in business. Working with partners you trust means a whole lot of overhead you can simply skip. An analogy: if I trust a plumber to fix my sink quickly and professionally, I can go get a burger and leave him to it. It's only when I don't have that trust that I have to pay the additional overhead of having someone I do trust watching to make sure he's not napping under the sink.
Want to see a business manager go into a dreamy fantasy? Ask them what it'd be like to be able to trust their software developers (in house or not). The more experience they've had with developers the more intense the fantasy.
The Rubber Meets the Road
We have a couple of areas of friction in businesses that exacerbate this situation. The main disconnect with business managers is that we have borrowed terminology and tools from other disciplines without understanding that our processes are fundamentally different. It's tricky because the temptation to use manufacturing terminology is immense. After all, we are creating a product of sorts. This makes so much sense on an intuitive level that it's hard to realize that the comparison is misleading and potentially dangerous.
I wish we could retrain everyone to make analogies to other business specialties. Scientific research or law come to mind as potentially useful analogies because both are similarly plagued by the impact of unique situations, changing ground rules, and unforeseen complexities. It would be interesting to investigate how managing software development like a patent application or drug research would change how we look at the problems involved. We might have stumbled onto iterative cycles and responding to altered requirements a whole lot sooner, for example.
The real problem, though, is that most developers (and even most development managers) don't take the time to learn about common friction points. Nor do they take the time to build relations with their business counterparts so that you have some political capital (aka trust) to use when it is needed. It's easy to forget that much of the progress in software development practices are pretty recent in terms of business processes. After all, business managers don't move at the speed of light and changes tend to take time to penetrate those layers.
Which means that a whole lot of industry advances aren't even theory yet in the board room.
And the fact of the matter is that you cannot expect a business manager to understand what makes Agile practices work. Or the reason that strong unit testing saves time over the long run even though it takes more time up front. Learning to communicate at a level that is sufficiently detailed for smart business decisions without getting bogged down into the jargon inherent in any specialty is an invaluable skill, and one best learned earlier than later. That means thoroughly understanding those theories yourself--not just on the surface or in buzzword compliance. It also means learning to communicate that understanding from orbit, 30,000 ft, 5,000 ft, and right on the ground. This is hard to do. It takes practice. It also takes exposure to business manager types. I'm not sure which is harder...
Something to think about, though: not learning this skill leaves you at the mercy of those who do learn it.
My point, though, is that it takes both. You have to learn your profession so thoroughly that you can deconstruct its "best practices" ("design patterns", whatever) and rebuild them from basic principles on the fly. AND you have to learn to communicate that understanding comfortably to people of varying familiarity with software development in a business environment.
That's what it takes to be a true professional. It's easy to let those two skills fall out of balance. Individuals who understand both are invaluable to a company. Also rare. Companies who discover someone capable of both are often surprised at how much smoother things run with that person placed where they can do the most good--a point Jeff Atwood's latest on becoming a better programmer drives home.
So I don't have a formula for quick and accurate estimates. Just a lot of hard work. Still, here's a tip for free: anyone asking for a firm delivery date is inherently assuming BDUF. Once you know that, you know where to start your answer.