Feeds

It’s anybody’s guess

Estimates, not guesses, are key to controlling development

The Power of One Brief: Top reasons to choose HP BladeSystem

Comment If you were to ask me how long it takes me to get to work each morning, I would tell you, “It usually takes about an hour, door-to-door.” I’m pretty sure most of you could also give a reasonably accurate description of your journey to work, too.

It’s worth bearing in mind the use of the word ‘usually’ in my answer. It does usually take me about an hour to get from my home to my office but occasionally, too occasionally for my liking; it can take a little longer. Not withstanding mishaps, however, my experience tells me the journey will be about an hour and I can plan to leave home about an hour before I need to be in the office and expect to be there on time.

This is because I know to a high degree of certainty the value to assign to most of the variables involved in the journey. I have experience of travelling to my hometown station; riding on the train; and getting from the destination station to the office. In other words, when you ask me how long it will take me to get to work I am estimating under conditions of certainty.

There are three conditions under which we can attempt to estimate anything and these are certainty, risk and uncertainty. We’ve already discussed certainty and under these conditions in software development, we would be familiar with using the technologies and we would have experience of the domain too. Estimating under these conditions is quite simple and relatively easy.

However, unlike with my train journey, it is very unusual for software developers to be asked to estimate from a position of certainty. To gain a competitive advantage, organisations need to be delivering new and, hopefully, unique functionality. "New and unique" is, by definition, something we have not done before and have no experience of. It is, therefore, unknown.

When we’re trying to estimate with unknown variables, we are estimating under conditions of risk. Under these conditions, we are certain about some things but not about others. For example, we might be planning on redeveloping our existing application in a new language. Obviously, in this case, we’d be familiar with the domain but not with the technology, so that is where the risk would arise. Estimating under these conditions is complex and difficult.

The very last condition we might be asked to estimate under is uncertainty and this is where we are unfamiliar with both the domain and the technology. It is very tempting to leap into this type of project just for the learning experience or the sheer thrill of doing something novel but, ultimately, it is doomed to failure. These are chaotic conditions to say the least and any estimating you did here would only be guesswork.

A frequent mistake made by developers and project managers alike is to imagine that they are estimating from a position of certainty when they are really estimating under risk or uncertainty. It is a human failing to believe you know more than you actually do or to over-extrapolate from your experiences. Guessing is easier and requires less effort than making a proper estimate. So, what should we do when we’re asked to produce an estimate and we are operating under risk or uncertain conditions? Well, it may sound obvious, but if we can bring the risky or uncertain variables into the zone of certainty, we can estimate with confidence.

Seven Steps to Software Security

More from The Register

next story
Secure microkernel that uses maths to be 'bug free' goes open source
Hacker-repelling, drone-protecting code will soon be yours to tweak as you see fit
KDE releases ice-cream coloured Plasma 5 just in time for summer
Melty but refreshing - popular rival to Mint's Cinnamon's still a work in progress
NO MORE ALL CAPS and other pleasures of Visual Studio 14
Unpicking a packed preview that breaks down ASP.NET
Cheer up, Nokia fans. It can start making mobes again in 18 months
The real winner of the Nokia sale is *drumroll* ... Nokia
Put down that Oracle database patch: It could cost $23,000 per CPU
On-by-default INMEMORY tech a boon for developers ... as long as they can afford it
Another day, another Firefox: Version 31 is upon us ALREADY
Web devs, Mozilla really wants you to like this one
Google shows off new Chrome OS look
Athena springs full-grown from Chromium project's head
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Securing Web Applications Made Simple and Scalable
Learn how automated security testing can provide a simple and scalable way to protect your web applications.